Google Blocking Sideloading of Apps? Effect on De-Googled Phones

Developers were recently informed by Google, including me, that signing keys are now required to be completed for all apps. That in itself isn't particularly new but Signing keys were used to validate your app with the Play store.

Now the validation will be done on device which means Google Android will "check In" with Google to verify the identity of the app and to validate the operating system.

This has obvious problems for non-Google operating systems like iODE OS, LineageOS or BraxOS.

This means you can't sideload an app from an unofficial source. But it could also be used to lock the ecosystem so we're forced to install only Google apps on approved Google OS versions.

Let's study the implications of this. Aside from sideloading apps, there are apps that come from F-Droid for example, will these be blocked as well? We'll need to study what this means.