A few years ago I wrote a custom SSH server to do exactly this, but for webhook development rather than tunneling to a pi. other peeps found it useful so it's turned into a bit of a side project. If you want to have a go before spending time on setting up your own server run "ssh -R 80:localhost:8080 ssh.localhost.run" to tunnel to localhost:8080, you'll see an internet accessible domain returned to your terminal.