the rigidness of some classes tied to some alignment is being progressively removed in the several iterations of D&d, PF, etc, for good reasons IMHO.
In PF 2edition the Champions (It´s the new class that replaces paladins) could be neutral. chaotic or even serve evil gods. The paladin champions are still lawful good, but you have champions of all flavours. You still have to pick a god and follow some tenets of the faith and clauses but the alignment spectre is broader. ( liberators for chaotic, the neutral redeemers or the Tyrants, antipaladins or desecrators for evil gods)
The only "vestigial rule" still in place is the tradicional "Druids cannot use metal armor" thing, a staple of druids since almost the beginning. For monks, druids and other classes more than following an aligment restriction, they have some taboos or anathemas that could make you lose the favor of your patron and you could lose your class powers, like comminting crimes against nature for druids, etc.
