Plexamp will already find songs of artists on compilations where they’re not listed as the album artist.
There’s already an existing suggestion discussing an option to fully support tracks with more than one artist (e.g. mutual projects, featured artists…). I suggest you comment/vote in that thread in order to help us avoid distracting or cannibalizing votes.
This is not about compilations. Currently if I search for song by artist “Microsoft” only songs by Microsoft will appear, not song where Microsoft was the featured artist. My library has singles as well as albums. I make sure they are properly labeled at Musicbrainz.
Examples:
Me searching for Megan Moroney(not all songs):
This is different than that, this more about search working properly. In my first picture not all the songs under her are listed despite Musicbrainz data.
The way I understand that suggestion is that Plex should fully utilize the detailed artist information per track — that’s including being able to search and filtering them individually.