[patte]

Yes, fly.io allows you to expose a UDP port. See the fly.toml [1] in the repo. Make sure the tailscale port is pinned [2] to the exposed port (41641 in that case).

I just tested it again and the connections are made directly (after the first 2,3 packages go via DERP):

    tailscale ping fly-ams         
    pong from fly-ams (100.96.123.32) via DERP(ams) in 15ms
    pong from fly-ams (100.96.123.32) via [2604:1380:4601:d605:0:6c3b:eed5:1]:41641 in 12ms

    tailscale status
    100.96.123.32   fly-ams              patte@       linux   active; offers exit node; direct [2604:1380:4601:d605:0:6c3b:eed5:1]:41641
    100.101.54.36   fly-hkg              patte@       linux   active; offers exit node; direct [2605:4c40:95:4eed:0:40f0:67b1:1]:41641

[1]: https://github.com/patte/fly-tailscale-exit/blob/main/fly.to... [2]: https://github.com/patte/fly-tailscale-exit/blob/main/start....