Personally I think Apple will, but I have enough doubts that I don’t want to make that claim.
> Most importantly, the EU may feel the same way.
That’s the rub. The EU has been arbitrarily writing new laws which mostly target foreign tech companies that don’t quite read “show me your bellies so we can pick out the choice cuts” but they’re pretty close. So the EU might do a lot of things, but if there’s an argument against them doing that, it’s what I said in my first comment above: it’s not worth any jurisdiction’s time to do so. That includes the EU.
You might need to support some technologies to get government contracts, but nobody ever mandated you had to support POSIX or J2ME or whatever to sell a computer or phone to regular people. That would be asinine, and a PWA mandate would also be asinine.