I had converted Ironfang Invasion to Pathfinder 2nd Edition rules, back when Age of Ashes was the only PF2 adventure path published. The crafting rules in PF2 are much slower and demand more raw materials than the PF1 crafting rules. And, of course, the PCs could not simply walk into Phaendar to buy materials after the Ironfang Legion conquered the town. I was worried that they would have trouble crafting arrows. That worry was wrong, because they looted plenty of arrows off of dead Ironfang patrols. Nevertheless, I invented a system for gaining raw materials for the forest. That might have the flavor you need.
Basically, they hunted in the forest not for food, but for plants and minerals that made good raw materials. I used Survival for the skill check and the DC was fairly easy because Fangwood Forest feels very lush. That will make the crafting feel more natural.
As for using an acorn in place of a pearl, acorns are too common. You want a rare plant with mythology behind it, like a four-leaf clover or mistletoe or hawthorn berries. This is a good time to ask the players for suggestions what they would think would feel special. Finding the special plant or mineral would have a higher DC than regular raw materials for magical crafting. "Oh, you rolled a natural 19, which sums up to 25. You did not just find raw materials, you found mistletoe."
I see no reason to get caught up in the minor details of crafting. A Pearl of Power (1st) costs 500g to craft. If you want to let your Druid reskin the pearl into an acorn, that’s totally fine. The cost is for game balance, and need not be exactly what the item says it is in the CRB. As long as you and your players understand that and don’t mind just saying it costs 500gp-worth of…”Magic stuff” to imbue that acorn, well, that’s fine. I personally would have my players make skill checks to look for materials, considering you’re cut off from civilization, though. Maybe dropping in a random traveler who happens to have some “magic crafting dust” for sale? Ultimate Wilderness has some decent rules for salvaging magic powder from unwanted magic items that can be repurposed into materials for crafting. Or maybe just replace a certain percent of treasure with crafting materials. Or if that feels like too much work and you don’t think it’ll kill the immersion, just have them spend raw gp and don’t think about it too much.