My biggest issue with the Oracle is that it's a Divine Only class. Tempest and Fire should've been Primal list; Cosmos and Lore should've been Occult; Ancestry, Battle, Bones, and Life are fine as Divine (though an argument for Life being Primal could also be made). I know that gets into Sorcerer and Witch design spaces, but Divine Access could be limited to the Divine spell list mysteries and Sorcerer ends up with more flexibility without needing to manage a curse.
To put it a different way: nobody is going to look at the Divine Sorcerer ancestries and say "Sorcerer is really crowding out the Oracle" or the reverse of "Oracles are really crowding out the Divine Sorcerer ancestries," so I don't see why it would be problematic for Oracle to have access to Occult or Primal depending on their mystery.
As for the flavor, Oracle has always been about a Divine curse, but that was a design aspect from PF1 where you had Arcane and Divine as the two schools of magic *and* Oracles received many more on-theme abilities through their selection of Boons as they leveled up, so there wasn't as much of a need for them to have access to a list that wasn't the Cleric list.
In PF2, many more of the Oracle's capabilities are tied directly to their spellcasting (since the Curse and Focus Spells are really only a handful of effects compared to what could be acquired previously through Boons). In addition, there are *no* Mystery-specific feats for Oracles, which is also very sad. As a result, I think it makes sense to broaden the flavor of Oracles from "Divine Curse" to a more nebulous curse cast on the target by an array of entities ranging from deities or other aligned outsiders (divine); to the unknowable cosmic forces of the Dark Tapestry (occult); to the Fey or Green Men (primal).
Or maybe make it so that Oracles can always choose the Divine spell list regardless of their mystery, but some mysteries (as listed above) can instead choose the Occult or Primal spell lists.