fyi you can use the deck restore image on an amd build, although probably there will be complications
https://help.steampowered.com/en/faqs/view/1b71-edf2-eb6d-2bb3#reimage
afaik chimeraos is the recommended alternative, which is a fork of the current steamos, with more supported hw (but not nvidia)

in theory, comet should handle it, but it is inconsistent for me. does it depend on the game? for instance, i only got achiements in brigador, but i played art of rally, dungeons 2-3, and a couple others which should have achievements, but didn’t get any

tbf with heroic launcher starting to implement comet (galaxy api), it might not be needed anymore

osx has an even lower market share (at least according to the steam survey), and they made one for it

but think of the achievements!!