Meiro is a native desktop player for YouTube Music. It draws its own interface in a native window instead of wrapping a Chromium-based web front end.
It's built with MyGO. The name comes from one of MyGO!!!!!'s songs, 迷路日々. The title is written with the characters for meiro (迷路, "maze") and hibi (日々, "days"), but the song is pronounced "Melody" (メロディ). It's a pun, and I named the app after the first half.
Like Nook, I made this by prompting Amp and wrote none of the code by hand.
You can browse and play public music without signing in. Meiro imports a browser session to show your personalised Home feed and Library.
It's still experimental.