It's possible to. Are they? Correct me if I'm wrong, but they're not. They're going after Microsoft and not Google.
Not that it makes any difference since Edge is just reskinned Chrome now anyway. If it was still it's own thing I'd be rooting for Microsoft, at least up until they start to become bigger, then I'd turn on them.
It doesn't need anyone to convince devs to implement it. I can do it whenever I run an emulator of old console games already, and devs of those games never implemented it.
If Sony wants to add it as a hardware feature they can.
As far as the patent, hopefully it'll get denied but I doubt it. Once they have it it'll cost someone time and money to challenge it, even though it should be a slam dunk that it is neither a new idea nor innovative and novel. This is how a lot of these egregious parents continue to stand - the cost of challenging them is high, especially if some blistering idiot of a judge ruled in a farcical manner.