Apple's biggest competitor in the smartphone market uses Macs extensively. E.g., here they were in a meeting about their flagship product (hint: it's not smartphones):
https://www.youtube.com/watch?v=JtRJXnXgE-A
Not 100% Macs, but certainly the majority. I would say the Mac market share at that company is much higher than in the general public.
Apple OSs market share for computers is under 10%. They have always been less than 10%. The rest are PCs based — different versions of Windows. Linux was around 1%.
Also, interesting... Apple is not the leader in smartphones — Android OSs are. That was surprising.
Again, this makes sense. Apple smartphones and computers are too expensive and not a good value for the average consumer.