Hello,
The mixed-dimensional features are not (yet) in the main branch and then there is no way to access it from the PPA for now. We aim to release this functionality early next year.
I am not familiar with the Windows 10 subsystem for Linux, but as far as I know Docker can be used directly on Windows 10 (more details here).
The Docker image your mention for the mixed-dimensional branch has all you need to make use of these features (it has FEniCS installed with the corresponding branches + dependencies).
So I guess using the Docker container from Windows would be the easiest way.