I do want to know if the source will become available because I would like to also create a mode in which you can select a region and it will just RW to a text field all the units possible for every government type/MIC with a selected faction instead of doing it on a per unit basis
There is no plan to release the sourcecode.

You can see what units are available for faction in specific province in "Province Details" dialog.
You can open this dialog by Manu "View" > "Province Details" or by key combination ( Ctrl + p ). Check Manual for details.
You can also copy data from list by marking rows You are interested in and pressing ( Ctrl + c ).
You can then paste it to whatever program You like.