Code signing is good, I like it, I approve, but it is a big obstacle for me personally and others who cannot afford Apple Developer Credentials.
Does the license of your application somehow prevent you from following whatever Apple wants to do regarding signing? I think there are plenty of apps/games out there built on FOSS technology yet they're still signed and run like anything else signed on macOS, but maybe I remember incorrectly?
Some developers avoid paying for the Apple dev program on principle. Joining it could be seen as supporting Apple's attempt at building walled gardens.
There's also the operational challenges for open source like who will sign-up and how to secure or maintain the signing keys etc. It brings in lot of friction.
Using individual developer account means exposing private information of one of the developers (which not everyone wants) and is a major buss factor.
Doing it properly with organization account means nontrivial amount of paper work to establish either a commercial company or an officially registered non profit. There are very few open source projects big enough for this.
So the only question is communities desire. There is no technical problem here.
Just financial and organizational one. Not every open-source project is going to do that.
Not sure why Apple had to change how Gatekeeper works. I will have to look for an alternative once my mbp dies. It gets tiresome to fight with the OS for every other app after every update now. Especially when it worked perfectly OK before.