This is really great news. And it really works. Starting on the ROCK, I set up using my AppleID (Sign in with Apple) and created a passkey. I saved the passkey on my phone. GoogleID is also supported. Both use passkeys.
To bring the phone up, download Tailscale from the iPhone App Store. Start Tailscale and follow the prompts to sign in with Apple (or Google if you like).
Anyway, Well Done, Roon Boffins!