Don't forget that UWP targets only Windows 10 and moreover it unifies development cross Desktop and Mobile. So we can read React UWP as small support of easy deployment to Windows 10.
There is no support of ReactXP for Window 7/8 so there is again Electron+Web as only viable option when using ReactXP.
Comments
You can address MacOS and Linux with current support. Just pack web app in Electron.
Then why would Windows need explicit support?
Don't forget that UWP targets only Windows 10 and moreover it unifies development cross Desktop and Mobile. So we can read React UWP as small support of easy deployment to Windows 10.
There is no support of ReactXP for Window 7/8 so there is again Electron+Web as only viable option when using ReactXP.