not that i kow off, but roughly simething like this:

1. I note the port and IP the bitaxe runs on.

2. install and configure nginx with reverse proxy in the rpi, and where proxy_pass is yhe bitaxe ip and port. https://docs.nginx.com/nginx/admin-guide/web-server/reverse-proxy/

3. install and configure tor with hidden service on the rpi. https://tb-manual.torproject.org/onion-services/

4. go back to your nginx config and add the onion address to server_name.

5. pissibly reboot. check some logs and visit your onion address using torbrowser.

Note: you do not need SSL certificates since the onion address works with asimilar cettificate tech.

I have a great time with hidden services, it makes it so I dont need DNS!

hope this helps