Its quite simple really;

It’s just a 31990 with a k-tag of the NIP-46 kind (24344 or something) and the 31990 profile data should have a _@domain as its NIP-05 that validly resolves to the pubkey that published the 31990.

If you want to peak under the hood the fans site I showed in the video is already deployed so you can play around with what I used to make the demo video (although I’m not 100% certain that I deployed the most recent version)