Another problem I faced with Orbot is that if you want to use it in vpn mode but with only selected apps you cannot enable the "always on" mode, otherwise the others apps don't work, but with this setup if Orbot crashs/disconnects the selected apps are free to use the main network and so leak.

Waiting for multi-vpn support (perhaps is GrapheneOS working on this?) built-in Tor support in an open source app fixes this.