I thought the Whatsapp desktop client was just a glorified remote control for the phone, and could not actually function as a standalone client by itself?
I am not on prince's side, just saying ...
If you're thinking of a state actor except Saudi Arabia, I think there would be much easier and more discreet vectors to Jeff Bezos Whatsapp than MBS phone (literally almost any of Bezos other contacts would be less risky).