Given how upstream (Moxie Marlinspike) opposed the redistribution of the Signal Android app by third parties, and recently asked not to Debian package libsignal-service-java:
https://github.com/signalapp/libsignal-service-java/issues/50 I suggest contacting him before doing any work towards the packaging of Signal-Desktop, unless we want to work with an hostile upstream. In this case, the least that would need to be done is renaming Signal-Desktop to something else, and possibly changing its icon, as their redistribution is considered a trademark violation. Paride