It's expanding beyond the valley, at least I can only speak for the PNW which is admittedly still a minor tech hub but not the level of the Bay Area. My own company I work for included (a change driven by myself) has switched almost everyone to macOS, as have many of our peers and competitors (non tech companies).

I'm also starting to see a lot of Macs pop up in smaller private practices - most dentist offices around here are on Macs, a few dealerships have moved over, etc.

Windows is still the majority by far, but its marketshare is slowly being eroded away. It'll be a while before F500 enterprises move over, if at all, but small-medium businesses are definitely growing their macOS usage.

I work at a large F500 company and I would be shocked if Macs were more than 5% of the total computer inventory. Excel alone is very sticky. Excel excerpts will tell you that Mac Excel is weird and does not work correctly.

Said as someone stuck on a windows machine with all of the corporate monitoring spyware which makes performance crawl.

I'm definitely seeing it consistently on the East Coast.

depends if you look at advertising as a sector it's almost 90% mac.