I know 2 baby boys called River.
Not my cup of tea personally, which is weird as I'm usually all for variety and 'different' names. I don't know, I think it sounds more like a girls name (again I usually think that's a stupid statement) and a bit too try-hard.
I think it's the new Arlo, lots of parents simultaneously thinking it will be v unusual, so there turns out to be a lot of them.