Excellent! I'll be trying it out.
iOS / Damus fam: TIL Orbot actually has been released for iOS!
Download it here:
https://apps.apple.com/us/app/orbot/id1609461599
Once it's installed open the settings and enable the option labelled "Disable Orbot for non-onion traffic."
Now any traffic to an onion service on your iPhone/iPad will use Orbot's SOCKS5 proxy transparently.
This should mean my Tor relay will work on iOS!