The Apple Touch icon is used for sites pinned to the home screen on iOS and for favorites on the start screen of MacOS Safari.

The AcousticBrainz, BookBrainz and MetaBrainz sites all properly support this feature. The ListenBrainz and MessyBrainz uses scaled-up versions of the plain 16px icons. The Cover Art Archive, CritiqueBrainz, MusicBrainz and Picard sites don't have any support.