Thank you for those.
I think I have the Windows and the Linux detection set up correctly. I don't have a Mac to test with, but looking at the code I am trying to update, I need a bundle name (such as 'com.github.atom' for the Atom editor) and the relative path to the install location for the actual program to execute (such as (installPath, 'Contents', 'Resources', 'app', 'atom.sh') also for atom).