That’s exclusive to iOS/iPad OS. There aren’t any such restrictions on macOS.

That’s a shame. I wouldn’t bet on Google Pay ever working on GrapheneOS.

Google Wallet didn’t work last time I checked, but contactless payments worked perfectly well by setting my banking app as the payment app.

Not all banking apps work due to the system integrity checks they do. Support for your banking app can probably be confirmed here.

I’m not going to claim that this year is the year, or that any will be. In regards to gaming though, two years ago the number of games which worked through Proton was quite a bit lower, and the number of anti-cheats which worked was effectively zero.

Anti-cheat support is still far from 100%, but it is significantly higher than it was even six months ago. It looks like it will only get better from here.