Wavlake, Fountain and RSS Blue have always made publisher feeds for artist and selfhosters can use sovereignfeeds to make their own. I've been building this into Music Side Project 2.0 to make it easier for self-hosters.
The issue is tying all of these together across different hosts.
Could we make a publisher feed of publisher feeds maybe but each host would have to be onboard so you can add that info into the feed.
What I do with StableKraft.app is if you have a publisher feed I make a page for you, with the publisher feed content at the top and label it as official and then search my database for anything that matches that same artist name and that stuff gets added to the bottom of the page as other releases.
For Longy since the names don't match he has 2 publisher pages on SK right now.
@Oscar Merry I'm open to any ideas you may have.