Unpacking Google’s Web Environment Integrity specification

"This website is not compatible with your device"

I can see this show up on Youtube (why not - under Google's control, and they want you to watch the ads on their official browser) and on banking apps. Initially. In the longer run, it either withers and dies, or it leads to antitrust action. I really can't see another way.

Actually, absent a full chain-of-trust from boot, which I believe Android/iOS do provide, and possibly the proprietary desktop environments can provide, it should be possible to fake the "I'm a legitimate browser" exchange. Which is what the 1% that care will do. But it sucks to have to go to deep underground "crack" type stuff where before there was an open web. Not to mention the risk of getting hit by the banhammer if detected.