Practically, verified boot is hard to not have a "this phone has been tampered with" message on boot, the backups generated often have encrypted user data that is usually wiped on boot-loader unlock, you'd also need to unlock the phone or have the user give the pin over and most of the apps that implement root checking SDKs would prevent them from working.

I'm not saying its impossible but it is hard to do at present in a way where if I came and picked up my phone again, I'd not know something happened to it.