I was curious why there was no hiphop examples and I found one on the Soundcloud page which wasn't very listenable yet, which probably explains why they skipped it:
There are several! Their Sample Explorer has a lot of them, but a lot of them are indeed not very listenable. I like this one: https://jukebox.openai.com/?song=787891207
https://soundcloud.com/openai_audio/snoop-dogg