23Sha-ger I think these are two different things. There's the developer verification thing (enable dev options and wait 24 hours or install via ADB) for non-Play-Store apps. That doesn't impact GOS at all.
This seems like something fundamentally similar to the device attestation app that GOS already has. It only matters on installation and not upgrades: once you install GOS (or any other OS) and relock the bootloader, you can't install an OS that's signed with a different key without unlocking/wiping first.
Probably this will be some built-in app, similar to the current GOS attestation one, that reports whether the OS is "official." GOS could either remove that code or just accept that it'll report that GOS us "unofficial"---which is true---just like the current "yellow" bootloader state.