Yes, the issue here was code signing. Mac really demands signing of apps now and blocks apps that aren’t fully signed and “notarized” which is why there were so many problems getting PsychoPy to run at all on the mac recently.
The version of pygame I had on my mac refused to code-sign because they were using SDL libs that are compiled on old versions of the mac SDK (I think is the reason). I wasn’t able to fix that issue quickly - I believe I need to install a “dev” version of pygame 2.0.0 to get more recent binaries but that will need testing to make sure nothing breaks
Workaround1 : use a different sound engine. Pygame has pretty much the worst timing of all the options. Is there a reason you need it?
Workaround 2: you should be able to get pygame working by installing it to another python3 installation on your system and then pointing PsychoPy preference for additional libs to include that folder