most browsers don't let you connect to localhost sites from remote sites no way no how

the only way it could be made to work is if you had a wireguard tunnel set up remotely with a remote address (DNS or just IP) that the local bunker or personal relay connects out to in order to make the round trip

the other caveat is that because the inbound connection has to go out to the remote address first you are essentially sending signals in a loop out to the remote and back to talk to the local device

it is vaguely possible that if you simply have a wireguard address for the bunker it routes directly to the address of the local device, and another possibility is using the hosts file to spoof that the address is remote somehow, i dunno what is possible but this is one of the most irritating things about web browsers

possibly if the app was also hosted locally it would bypass this limitation