Yea AA works as I said. For GPay "huge inconvenience /s" Just get a case with room for your cards , issue resolved. I said it was lazy ,pointing out one small thing like that is just trying to find something to blame, imho.

But if you really want Gpay, get a ROM and flash gapps on it . Mileage may vary so check your phone and roms.

Never used watches but yea I assume it might work. Seems so, https://support.google.com/wearos/thread/215767/can-i-use-google-pay-on-a-wear-os-watch-if-my-phone-is-not-nearby?hl=en

I never used stock OS on pixels but of what I read it is a world of difference with something better on them.

I never had any issues on GOS , basically everything works even without sandboxed Google. For the few things that don't I keep it in a separate profile. (Which really is separate in contrast to stock)