Is it possible to have a list of de-federated instances from Beehive? I think it may be good for transparency, even if I am pretty satisfied about how things are being done here!

Right now I am testing Kagi, which is a paid alternative - from a privacy point of view, it looks great, and the results are good. It also has a lot of additional features that suit me well. No Maps integration though. alternatively, I can recommend SearXNG, but it involves a bit of tinkering.

And there are so many campaigns, it is incredible.

Indeed, if I were the developers I would be threading much more carefully. While it may be true that the letter is not precise enough, access to YouTube implies a relative acceptance of the terms of service of providing the service, and it is not so clear cut as Invidious claims.