We discussed this prior to launch, and obviously decided to launch as you see it. :) Our reasoning was that a) standardizing on GitHub URLs makes it easier to do automated analysis as part of the funding model, and b) any project important enough to matter will have at least a GitHub mirror. If you have counter-examples to (b), please comment them on GitHub (see what I did there?) or here and I will copy/paste for you. :)

https://github.com/osendowment/endowment.dev/issues/34

https://gotosocial.org/

Out of ethical disagreement they switched completely to codeberg. And they are certainly not the only ones, given signaling on the fediverse by other EU citizens.

> any project important enough to matter will have at least a GitHub mirror

That might be true, but many of the mirrors are unofficial.

They haven't pulled the plug on github yet, but my understanding is that Gentoo intends to drop it long term. In general, I would expect any of the projects that leave GH because they want to avoid being used to train AI would avoid leaving even a mirror behind (since that would defeat the point). (This is not intended as a value judgement, just saying that there exist projects that are doing this)