Microsoft abandoned their Windows Mobile OS years ago.
(I'm not sure there's ever been a proper decent portable/handheld that ran Real Windows; there's tiny laptops from the Libretto to the GPD Pockect, which is a nice machine. Or there were handhelds that ran Windows CE back in the PDA era. And I've seen very cheap 8" tablets. But a phone-size form factor? Not quite. I suspect the never completely fixed UI scaling is a problem there.)
2) relative pointer position makes small controls extremely usable. You only want absolute position for the keyboard.
Not as obvious a decision for some.