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
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