Agree with the other answer, just no incentive for third party developers.

With Apple it really is a transition, with Windows, it's well under 5% of PC sales, so probably under 1% of actual computers in use.

Apple is 100% on board with ARM, Microsoft isn't and the OEMs even less so, you can barely buy an ARM Windows desktop, only thin laptops.

Where I work, we ship Windows desktops for an industrial application, and we haven't even had a meeting about supporting ARM, it's like they don't exist.

Making ARM machine that fulfills Windows requirements is harder than making your typical throwaway arm gadget (and then you hit things like Qualcomm not implementing it right either).

There is not much profit for a hardware maker, and thus little install base for software makers to care

Microsoft can't never be, because unlike Apple, they are mostly a software company, they depend on OEMs wanting to come for the ride.

They aren't alone on this matter, this kind of stuff has equally plagued other open systems like CP/M, UNIX, MS-DOS, Android, where a product might come from multiple OEMs and each has their own agenda for differentiation and keeping their customers around.