Re: new fangled Windows Subsystem for Linux
Essentially 21st C version of the old MS Services For Unix, slightly updated.
It's not even remotely close to being that.
if you want to dual boot, or run Ubuntu in a VM on Windows (the reverse is better), then get Ubuntu or any other Linux distro (or BSD etc) in the normal way.
Why bother? If an Ubuntu user land installation cannot tell the difference, why both dual booting or going the whole VM route?