I think adding ListenBrainz and/or Maloja support would be phenomenal, but for me it’s one step at a time. Right now I have an open PR into PleromaBE to make it so that the account/pleroma section in the AccountView JSON has a scrobbles entry, which is an array of the most recent five scrobbles, if any. You can see that PR here: https://git.pleroma.social/pleroma/pleroma/-/merge_requests/3975
I’m doing this because as it stands, my implementation in the FE requires hitting the endpoint, and in order to make it avoid absolutely inundating it, I have to throttle it. This would obviate that completely and allow me to just look at the returned account data normally, as with most of the rest of the API.
So far Lanodan seems reluctant to add it, saying that Listen is in itself a “hack” that first (he stresses that word) must be redone. Basically, the complaints about scrobbling are that they aren’t supported by FEs, but then efforts to support it get rebuffed.