Literally just the eyes blinking.

thats correct

They could've done more, I think. Like making them move along in the water, or have the arm holding the drink move a bit.

well, I could say how the ring looked, what kind of drink he's holding, my fursona, water particals moving, and normally it would be a tail wagging, what was not possible for my bunny, so the artist gave me some possibilitys what else she could animate, I desided for the blinking, and thats for only 10$.
and the blinking animation looks smooth and good, so I guess, I got a good deal with "only" 10 bucks ;3

I suppose you did.