Codeberg for public repositories, cgit (if that even counts) on my own server for private ones

I personally use Claws Mail.

It’s Proton. What do you expect?

I’m not a fan of GrapheneOS, but the point they bring up here is valid. There is already proprietary firmware on your computer. There’s no reason why you shouldn’t be updating it to protect yourself from serious exploits. The FSF takes an ideological stance rather than a practical one, unfortunately.

What do you mean by “without proprietary bs”?