I used them as well, and I know of at least 3 more coworkers who use them as well.
I got started when I got one for free with a used computer I bought. I've since then switch full time to using an MX Ergo (like OP) on my desktop, and a cheaper M575 I keep in my laptop bag.
I even game with them, and haven't touched a computer mouse in probably 2 years.
The MX Ergo is far superior to any other I've used, highly recommended.
I bought a used gen1 Thinkpad X1 Nano. It is super light (<1kg), works flawless out of the box with Linux, and while I think it does have a fan I've never noticed it.