I know this is a bit late, but this question has been in my head since it was posted.
I knew there was a solution out there.
This does involve the use of another app called shuzuku which allows adb/privileged permissions. It's a very simple setup.
Anyway, this, i believe, is EXACTLY what you asked:
https://github.com/aload0/AppLock
Get it here:
https://f-droid.org/packages/dev.pranav.applock/
since the original maintainer of shizuku (rikka) has stopped updating, the best fork (with many improvements and features) can be found here:
https://github.com/thedjchi/Shizuku
The current apk is here:
https://github.com/thedjchi/Shizuku/releases/tag/v13.7.0-thedjchi