@rossk It's pretty integrated with the M.b. API. But that is an interesting thought.
So it is currently using IndieAuth and MicroPub, though hard coded to the M.b. endpoints. The discover page could work with a little tweak since I'm pretty sure you don't need an auth token for those feeds. And MicroPub should work if it wasn't hard-coded (the new post and manage post/media pages). Replies could potentially be tweaked to send as webmentions...
I don't think a custom IndieAuth endpoint would work with M.b. in terms of getting M.b. account functionality like the timeline feed, bookmarks, bookshelves, and the like. So those would need to be hidden.
It would take some thought to figure out the rest if you Like what would be in the timeline area/conversations area instead... π€ An indieweb feed reader via MicroSub? Assuming you have a server doing the feed fetching and parsing...
So I don't think it's insurmountable to do. It's something I'd have to think about; if I wanted to take Lillihub in that direction. Also, Lillihub is open source so anyone who's interested/or inspired can check out the code here. It's using Deno, so JavaScript on the backend. The front is just straight forward HTML, CSS, and a sprinkle of JavaScript.