Anyone running an ETH validator node on a Mac?

Or know anyone that has?

I want to start staking but stubbornly can’t bring myself to buy a PC. 

I can’t be the only one.

Do you want your Mac be running 24/7 ?
Not good imo.
You should buy a NUC instead.

Working on photogrammetry-3D - linux addict - Cosmos lover

I also want to help diversification of hardware and OS on the network

Good intention but the network decentralization doesn't care of os/hardwares.

As long as you are home staking, you would help the network in the better way possible, regardless of the OS/Hardware.