I realized that I need to know how to pronounce Ryugu too, and I also realized that I wasn't sure how Japanese speakers pronounce the name of its spacecraft, Hayabusa2. Fortunately, Tasker had access to a roomful of astronomy graduate students at Hokkaido University, several of whom carefully spoke the words for her and me: Hayabusa, Hayabusa2, and Ryugu. I thank them very much for helping me out!
Hokkaido University graduate students pronounce Hayabusa2 and Ryugu
Their pronunciation of "Hayabusa" is pretty easy for an American to replicate. I'm fascinated by the fact that Hayabusa2 is not "Hayabusa-ni" but instead "Hayabusa-tsu", a Japanese pronunciation of the English "two".
As for Ryugu, that one is going to be challenging, because the initial consonant is that Japanese sound that's somewhere between an "R", a rolled "R", and an "L". I think I'll go with "Ree-yoo-goo" as a first approximation, but that's one too many syllables; I'll have to practice that initial sound quite a bit before I get comfortable with it!