Not available in the U.S., most unfortunately. I pay for Apple One Premier — it’s cheaper than the individual services I’d want, I can share it with family, and I’m quite content with Apple Music.
So I’ve no need of nor interest in YouTube music. But I’m trialing YouTube Premium anyway, because I watch a lot of YouTube and find downloading videos using yt-dl or similar tedious. (I know I could automate that and drop things in Plex, but then I lose out on the extra information about the video, the links, and the comments, all of which are actually sometimes useful.)
If there were a Premium option de-coupled from YouTube Music, I’d be on it in an instant.