I guess this app can still be installed locally? It's just that it can't be distributed to others due to signing requirements?

Edit: Ah, it's in the article, this is about AppStore distribution. Walled gardens are going to walled garden.

The direct version is fully signed and notarized by Apple, just not distributed through the App Store. Anyone can install it from mitmllc.com/whisperpad without workarounds. The 2.4.5 rejection was an App Store rule, not a general restriction on the app.