[2023] Exit Code Null - Game won't open from Launcher - Mac

What if you run ck3.app and hoi4.app directly from Finder, do they work then?  

PadwiseGamgee said: No - If I run that, then Steam still opens up, the launcher opens and I get the same issue.

Running the .app files directly from Finder does not start the launcher. Did you perhaps do it on a desktop shortcut or something like that?