If you’re rooted, you can use Pixel Launcher Mods (or Pixel Launcher Extended, which includes Pixel Launcher Mods). It themes all of them but Libro.fm automatically, and you can easily add an icon for anything missing (either making your own or using one from another app).
Looking at my phone the main apps I’d like to see get this theme treatment is Proton Mail, Libro.fm, ReadEra, MX Player, FX File Explorer, Duo Mobile.
Then I’ll be satisfied that everything matches.
If you’re rooted, you can use Pixel Launcher Mods (or Pixel Launcher Extended, which includes Pixel Launcher Mods). It themes all of them but Libro.fm automatically, and you can easily add an icon for anything missing (either making your own or using one from another app).