Yeah we can give that a go

It could first try to extract the art from the song, but that doesn't work when using something like Mopidy and streaming music from a remote server.

It could then fall back on, or just rely on, something like MusicBrainz, who have an XML and a JSON API.

imv seems like the obvious choice seeing as it's lightweight and supports Wayland/X.

Alternatively it could be configurable, but that's impossible to express in e.g. a PKGBUILD's dependency list (similar discussion)