I have written https://github.com/efrecon/sshd-cloudflared to solve the same problem. It provides you with an SSH connection inside a transient cloudflare tunnel. The connection is only accessible to the SSH public keys stored in your GitHub account.
I've wanted to run it on my wear OS watch, but while you can sideload the APK, wearOS does not have a file browser, so it's not possible to import a planned route or similar. Has anyone here any idea for how to solve this?