If I were in your position, which I am and will probably end up doing this, is vpn into your home network and just connect to the local IP of your bridge server.

WG tunnel on F droid allows for you to auto connect to your wireguard server when you leave your home net, and auto disconnects when you get back on your home net.

Personally, I’m unsure if proton bridge listens for external request or if it only accepts requests from localhost? If that’s the case it may be an issue.