Windows ANYTHING is a kiss of death for anything other than desktop. They've done their best to drive people from it too with the stupidity of Win8 & Win10.
They need a desktop with best of NT4, Win2K, XP (Win7 was only a fixup of Vista, maybe use some bits of it).
Windows Phone, & Arm surface shows that a non-desktop MS system should NEVER EVER be called Windows ever again. Windows CE wasn't Windows. No "pocket" device can be windows as it needs a different GUI.
Desktop windows need legacy APIs, and x86-64, full backwards compatibility to all NT applications and many 16 & 32 bit non-NT Windows apps via NTVDM, WOW, etc. Not experimental new APIs and Run anywhere programs and a Store and slurping, XBox, VR etc all integrated.
MS are a mess since 2004.
Different platforms need tweaked OS, different GUI and different applications apart from perhaps simple widget like email and pure text note taking, or music / video playback.
A Browser made to have same GUI on mobile & desktop is crippled on Desktop. By all means use some commonality below GUI.