Unitree. I think it's equivalent to the Go1 which is ~$5k shipped (although I don't think that version gives you the SDK access needed to do these kinds of tricks). It's much smaller than Boston Dynamics' Spot.
It's the predecessor of Go1. If you buy the Pro/Edu version of Go1 then you get direct low level SDK control, though there are reverse engineering efforts that can do the same on the cheap ~5k version as well