Wait... there are "free Apple Developer Certificates"?
[0] https://synappser.github.io/downloads/ [1] https://support.apple.com/en-gb/guide/mac-help/mh40616/mac
I think (but am not sure) that you can use them (for now) to sign a macOS app that you distribute from your own download somewhere, and Mac uses can download your apps and click through the "Yes, I trust apps signed with that Satoshi Nakamoto certificate" dialog and install them.