>How many different models of PCs get released?

If you want to go that route, each manufacturer is responsible for their own drivers for windows, linux, and possibly Mac (though if it’s novel enough, they will do it). Then think about the components that make up a PC. Motherboard, CPU, Memory Control, IO, OS, Audio, Video. Each of those needs to release patches. So its orders of magnitude more than any Android OS. It’s just pure laziness on the hardware manufacturers that don’t want to invest in software/support. They want Google to do that.

But how are they doing to do the artificial market segmentation otherwise ?

(E.g. Samsung still limits Now brief to latest devices even though it is a 99% software feature + 1% cloud with 0 hardware requirements.)