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.
To prevent it using Internet at all, you can turn off individual apps access to WiFi and mobile data easily
To bind to a VPN, I use protonVPN, and I’m pretty sure the Android app has the split tunnelling feature to allow this as well. Not sure if that protects against leaks, but you could just have the VPN on all the time and use androids VPN settings to prevent any data usage outside the VPN