I saw this interesting feature proposal for Mastodon and so I thought if micropub team would also be interested in it.
The feature is allow a user with just @domain.tld address. It is compatible to webfinger specs and, how micropub is intent to unique-user instances, this feature can be very appreciated.
The description of the proposal is in the following link https://github.com/mastodon/mastodon/issues/22213.
All the best;
-- Filipe Saraiva https://filipesaraiva.info/