I watched the recent Giant Bomb Quick Look where they were playing on PC with a Dualshock 4 and noted the weird reversal of the confirm and accept buttons compared to the game played on a PS4. I did a bit more reading and I guess they decided to follow the Japanese PS4 menu style where 'O' is confirm and 'X' is cancel. This is compared to the rest of the world where 'X' is confirm and 'O' is cancel. I've seen some cultural reasons given for this difference over the years, though oddly enough Sony has made the decision that for the PS5 Japan will be switching over to the other standard,
which hasn't gone over well with Japanese players...
My UID is 600189945.
While I haven't actually tried co-op yet, my understanding is that all platforms are fully cross-play with each other; but you can't have any main story (or even side story) quests set as your active quest when you want to do co-op (it disables the menu option). I believe you are limited to taking on the various dungeons (domains), overworld bosses and daily commissions in co-op. The issue with the PS4 is that's it's not *cross-save* with the other platforms as your account is tied to your PSN, rather than a mihoyo account.