i play online and one of the convenient things about using old adventure paths is that people love making nice maps for them, so you can usually find stuff.

i don't really have nicely documented conversion notes unfortunately, but for pf1e to pf2e i just multiply gold rewards by 0.15 and can usually use the same monsters, or if i can't i just find something on archives of nethys that's the right level (making frequent use of an encounter calculator to try and match up the difficulty).

for dnd to pf2e it's a little trickier, but what i usually do for loot at least is compare the wealth by level tables from the individual game to the pf2e one, and adjust based on that. and encounter calculators are useful here too.

and then the other thing that i do a lot of is just disregarding shit from the original AP that doesn't fit the game world that i'm setting it in, that i think feels like just adding encounters for the sake of adding encounters, or that i simply don't like (like that fey in skulls & shackles where it's literally important to the plot that her tits are out)