I have been reading for some time now that MS has made a custom rom of Windows10Phone for the Xiomi Mi4... What I want to know, could it be installed on other android devices since it is a manual install from a PC onto Android device?
Nope, while you could try, remember that like a PC, phones tend to have cutom parts that require specific drivers and more.
All things considered, you would get a much better, more detailed answer over at XDA.
Needless to say, without some work on the actual rom itself, you will probably end up with a brick rather than a working phone... unless you are using the Mi4.