> non-app-store apps on Catalina are still required to go through them for "notarization" to be allowed to run on an unmodified OS

Apple tries to hide the option, but you can still run non-notarization software on a Mac. The first time you run the application, open in from the right click menu. It'll give you a warning, and if you select OK it'll run. After that you can just run it by double clicking like normal, and it won't warn you.