I’m asking for Android specifically, but I’m curious what else is out there.
For example, some apps work without internet but may use it if it’s available. I might want to block that without having to turn off wifi, force stopping it, and wiping the cache/data.
Similarly, maybe I only want to use the app over a VPN and want to prevent accidentally opening it without first turning the VPN on.
Aside from what the others said, my VPN (also on GOS) has a kill switch function, i set it to maximum and this way the phone simply can’t connect to the internet at all unless it uses the VPN.