I'm scratching an own itch here again and would like to share the result in case it's helpful. I have modified the track detail page to show a cover, providing a quick visual cue to differentiate between multiple track detail pages (across many tabs for example). It prefers a track's cover if it exists and falls back to the album cover.
I have chosen the large resolution cover because it's 600x600 and the column this is positioned in is approximately 300px wide both on mobile and desktop, making it too wide for the 200x200 medium square.
If this is good to merge I'm happy to add a changelog entry.