I would prefer not to have to install an app to install an app when I only need one... 

Hello,

The mac releases have not been signed with an apple developer certificate. I don’t have a sonoma device to test with, but:

You should be able to either: Right click (or control-click) the app in finder and choose ‘open’, and then ‘open’ in the dialog prompt

Or (as I think you’re referencing)

You can install the application through the itch.io app, which also makes it easier to update.