Noticed by the good people at Android Police, the Youtube for Android application now supports playback with a whopping 2160p resolution at 60 fps (4K @ 60), complete with HDR (high dynamic resolution). This will be really exciting news if there are just more smartphones that are able to take advantage of videos that are so crisp. Alas, there are only a handful.
If you happen to own a Sony device with their 4K HDR screens, this is a great day for you. As an example, the Xperia 1 II has a screen that it can use. I believe Sony has a few others as well.
I tested the playback on my Pixel 5, obviously useless as my resolution reaches 1080p, but I can confirm that the option is live. You only need to find a video that was originally uploaded in 4K with HDR. As you would expect, the options are also somewhat limited, but the number is definitely increasing as 4K adoption becomes more the norm.
Enjoy, Sony phone owners!
// Android Police