[tcd]

> they could make having this app a legal requirement to go in any shop if they wanted

If they can legally mandate an "app" they can mandate me having a device to run said "app".

It'd be absolutely absurd to mandate you having a spy with you at all times to exist in society.

"Sorry, don't have a phone, kthx", "Sorry, my phone doesn't use gapps, it's using a custom ROM", and what about these Linux phones?

Yeah, that's not going to work.

[IanCal]

The idea that the vast majority of people would not be running a stock OS seems less likely to me than measures like that being introduced.