That's really the thing with Steam in general, from a consumer perspective it's a very good and honest service, it actually adds to the experience of playing games instead of being an annoyance.
A lot of other stores feel like only shells made around popular titles to promote more stuff and lock people into using them. More launchers won't solve the monopoly of Steam, you'll just end up with as many as there are streaming services.
That's not the case for GOG and Itch, but there you don't get the same level of experience.
Won't work sadly, if you install a custom OS your device will not be able to attest to it being original, and play integrity won't pass (which would by extension include WEI). Not providing the results will be seen as just as bad as not passing. So as long as the vast majority of mobile users have it deployed you're screwed.
You can think of it as requiring everyone to wear a cryptographic ID badge to do something as simple as going to the store to buy groceries. You can always not wear it, but you will be denied service just as someone who has a "made up" ID.
The evil exists at the silicon level where they cryptographic keys are hidden from the user.