That kind of runs counter to the fundamental structure of APs. In each of them, the PCs all wind up with levels in the upper-teens by the end of the AP. There's no scenario where one could call that "low-power".
But as far as scope goes, I think we can judge in part by what happens when the PCs succeed (or fail).
I think these APs ultimately have a narrow scope. Pretty big spoilers within!
Curse of the Crimson Throne:
If the PCs fail, Ileosa becomes a powerful, immortal threat, but still just a regional one. If the PCs succeed, Korvosa essentially continues on as before. Either way, the world is not endangered and the effects are at worst limited to Korvosa's aggression against neighboring powers.
Legacy of Fire:
For all the elemental powers thrown around in this AP, the PCs' failure "only" results in the explosion of Pale Mountain and destruction of Kelmarane. Many people die, but the effects are restricted to part of Katapesh. Jhavhul/Xotani move on to the Plane of Fire. The long-term ramifications might be significant, but little changes for Golarion at large.
That said, the PCs are hopping between planes on the regular, and dealing with powerful elemental forces.
Kingmaker:
The entire AP's scope is limited to the Stolen Lands. If the PCs both play the kingdom-building game and are good at it, the Stolen Lands might become a significant force within the River Kingdoms, but that's about it. At worst, failure reverts the Stolen Lands to wasteland, with few effects beyond its borders.
The PCs do face a powerful fey queen in the First World. She's still a plausible threat for a low-powered game, but a GM could easily refocus the AP on more direct, mundane threats to the PCs' kingdom.
Carrion Crown:
Failing to defeat Adivion has no short-term effects on Golarion; Ustalav might suffer, so nothing changes there. Tar-Baphon is still sealed, and Adivion still has a lot of work to do. Outside of Ustalav, nobody would likely notice that much even happened unless Adivion succeeds at unsealing the Whispering Tyrant. The adventures' scope are also mostly limited to Ustalav, though they deal with alien forces from the Dominion of the Black/Lovecraft.
Skull & Shackles:
In my opinion, Skull & Shackles has the narrowest scope. The PCs don't face a threat to the world at large, they're just trying to get rich and run the Shackles. Failing the AP really only gets the PCs kicked out of the Pirate Council; the Hurricane King doesn't get stronger, he just consolidates his political power. Aside from some naval influences shifting around Garund and Cheliax, not much substantially changes to Golarion either way.
Shattered Star:
Even if the PCs fail, most of Xin's work goes toward conquering Magnimar and raising the city of Xin. While Xin is a threat to Varisia, and Magnimar is permanently transformed, the PCs' failure doesn't put Avistan--much less Golarion--in immediate danger. Even if the PCs succeed, few find out, and they're celebrated in Varisia but unknown elsewhere.
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In a couple of APs, the PCs' actions determine the scope of the effects:
Council of Thieves:
If the PCs fail, Westcrown becomes a tool of Mammon, which wide-reaching effects across Cheliax that set the stage for a long-term power struggle between fiends for the rest of Golarion.
But if the PCs succeed but don't build enough fame, not only does very little change in Westcrown, but the PCs might even be thrown in prison for their trouble. Even a significant victory leads only to self-governance; little ultimately changes. Only an outstanding success reshapes Cheliax by leading Westcrown to independence--even then, it's still a local victory at best.
If you tone down or remove Mammon's role, this entire AP is effectively limited in scope to a single city.
Iron Gods:
Unity can become a powerful divine force in an unstable part of Golarion; failing the AP irrevocably changes Numeria, adds a malevolent new god to Golarion's cosmology, and leads to the malicious spread of technology across the world. Successful PCs can instead install Casandalee as a new, benevolent divine entity for Golarion, but her scope is relatively limited; most people outside of parts of Numeria won't know or understand her.
Also, the PCs don't have to grant her divinity, nor do they have to expose the Technic League's secrets to the world at large; if they choose to, successful PCs can just become a new sort of Technic League themselves, devoted to limiting the spread of technology after seeing how dangerous it can be.
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The stakes of the other APs are far too high to ignore.
Rise of the Runelords:
Karzoug rises, just as it says on the tin. At best, Varisia falls in a year, and the rest of Avistan has to deal with ancient powers beyond their comprehension. At worst, Mhar rises and begins destroying Golarion (and Karzoug is still running around, though without his city or army). Either way, everybody on Golarion is screwed within a few years.
Second Darkness:
If the PCs completely fail Second Darkness, it's Earthfall 2.0. Hundreds of thousands die, Kyonin is obliterated, and every corner of Golarion (including the Darklands) is transformed for decades, maybe even centuries. Even if the PCs partially succeed, thousands still die, whether from partial meteor strikes or flooding. And even if the PCs completely succeed, they open the possibilities of a brutal war in Zirnakaynin that changes the Darklands, or even the threat of transforming Golarion's remaining elves into drow.
Jade Regent:
Failure plunges all of Minkai into a dark age and threatens the stability of Tian Xia. While the effects to the rest of Golarion are largely secondary, a wide swath of the world is deeply changed. If the PCs succeed, they're likewise best friends with Minkai's new regent (or one of the PCs is the new regent), making them instrumental parts of Minkai's and Tian Xia's history. Either way, in some small way the PCs are responsible for changing a part of Golarion that much of the world interacts with in some fashion.
Reign of Winter:
If the PCs fail, all of Golarion is permanently plunged into winter by Elvanna's ritual and Baba Yaga is imprisoned. If they succeed, Baba Yaga is freed and Irrisen gets a new queen, but not much else happens. Either way, the PCs go to other planets, including Earth, which won't fit well with a low-gonzo game.
Wrath of the Righteous:
If the PCs fail, the Worldwound rapidly expands. Within six months, Mendev, Ustalav, Numeria, the River Kingdoms, Brevoy, and much of Lastwall, the Hold of Belkzen, and Kyonin are consumed by the Worldwound. Galt is carved up by Taldor and Andoran. Most of Avistan turns toward halting the Worldwound's advance. The rest of Golarion is largely unaffected, but unless the Worldwound is closed, the world would eventually be consumed by it or devolve into eternal war against it.
Mummy's Mask:
Hakotep takes over Osirion and begins expanding across Garund, starting wars with Thuvia, Rahadoum, and Katapesh. This eventually disrupts trade with the Inner Sea region, dragging them into the war. However, if the PCs succeed, very little changes.
Giantslayer:
The Storm Tyrant has a flying castle, multiple dragons, and an army of giants. Avistan quickly turns into a very awkward place to live if you're under 15 feet tall.
Hell's Rebels:
If the PCs succeed, the scope is limited to Kintargo; they might inspire other revolutions, but the Glorious Reclamation is doing a better job of that anyway. But if the PCs fail, Barzillai Thrune becomes the Archduchy of Ravounel itself, and threatens to embody all of Cheliax, as a genius loci. A malicious, aggressive, expansionist genius loci in Avistan effectively rewrites the rules of nature for a swath of the continent.
That kind of runs counter to the fundamental structure of APs. In each of them, the PCs all wind up with levels in the upper-teens by the end of the AP. There's no scenario where one could call that "low-power".
But as far as scope goes, I think we can judge in part by what happens when the PCs succeed (or fail).
I think these APs ultimately have a narrow scope. Pretty big spoilers within!
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Thanks very much for the effort!
That's a good way to think about the question, I think.
