Okay, this was a huge hack on my part, but nfd (native file dialog) is the library used to display all the dialog boxes when you click on load sound. I could not, for the life of me, get the nfd make file to compile natively on my computer running mojave, I had to resort to the alternative xcode compile option in order to get it to work. This is the only place where xcode is used. So, if you can some how build the nfd static library using nfdās gmake system, you will not need xcode at all.
Just make sure the static library is placed in the correct location:
EmissionControl2/ecSource/external/nativefiledialog/build/lib/Release/x64/
So I would start there; I have opened up an issue in the nfd repo, so hopefully that can be attended to soon.
Hope this helps!