I’m not well versed enough in Android app development to answer whether or not one userspace app can even access the screen contents of another app without root or special permissions

This requires special permissions and explicit user approval every time an app starts screen recording, plus it shows a red notification whenever screen recording is active.

I think you could get by with a one-time user approval as a device administration or assistive app permission, which you’d need to manually grant in Settings. Unlikely anyone would do that by accident.

That might be different for system-level apps. I haven’t bought a carrier-branded phone in 10+ years so I’m not sure what that’s like these days.