

“WG Tunnel” on f-droid lets you define a config/native for either mobile or wifi, whichever you want.
two configs on both? It does that. A config on one and nothing on the other? It does that. It swaps whenever your phone moves from mobile to wifi or vice versa.

if neither is selected, it considers it “both”.



The tailscale method, bake it yourself. It’s all routing-based.
If you have a remote VPS and a home wireguard server and both are connected, then you have a remote connection outside of your home network. Make it a transit router. Then you’ll have your mesh and your VPN all in one, even if it’s still just all you.
Go a step further and connect mullvad to the vps and do a little routing work.
As for what routing work specifically, I couldn’t begin to tell you. Ai and some search-engine-fu might be necessary.
Here’s a (similar) example, even if he’s doing it backwards to my suggestion:
https://superuser.com/questions/1776851/routing-wireguard-peers-traffic-via-another-peer