Other tunnels
Use ngrok, Tailscale Funnel or any HTTPS tunnel you already have, and why a VPN app on the phone conflicts with the per-app proxy.
Fits when you already use a tunnel service on the PC. Does not fit when the service requires an app on the phone and you need the per-app proxy on that phone.
Any service that gives a public HTTPS address for a local port works. Point it at http://localhost:8779 and add the address with the wss scheme and /agent path:
ngrok http 8779[remote]
addresses = ["wss://your-name.ngrok-free.app/agent"]tailscale funnel 8779[remote]
addresses = ["wss://your-pc.your-tailnet.ts.net/agent"]Restart droidline serve after changing config.toml.
A VPN app on the phone
You could also install Tailscale (or another VPN) on the phone and use the PC's private VPN address as if it were on the same network. It works, with one catch: Android runs one VPN at a time, and the per-app proxy is a VPN. On a phone that uses the proxy, run the tunnel on the PC only.