VM should work. For B4i (ios) you need also a mac for compile afaik.
The output runs on win, linux, server, mac, ios, android or arduino. Depending on what you used b4a, b4i, b4j or b4r. The syntax is the same eveywhere.
The crossplatform libary b4x pages makes sure that the same program look and feel can be compiled to various platforms without to much hassle.
There is a massive amount of operating systems already. List of operating systems.
Why would you like to create a new one? A lot of the existing systems are specialized for use case and or hardware.
If you want something for general PC use then you have the software problem afterwards, an OS is useless without software support. You need a critical mass of supported software before it takes off. Means money and time.
If you want to make it windows compatible you have the copyright problem, if you are flying to close to the sun it will burn you before you get to your destination .
TL:DR to high effort, low outcome.
Edit: spelling