CS educators collaboration communities?
Strangely, just after posting a question I found a list of additional link collections:

https://github.com/zamansky/awesome-cs-education
https://github.com/quobit/awesome-python-in-education
https://cseducators.stackexchange.com/a/3947/9632

And one chat:

https://chat.stackexchange.com/rooms/59174

I still think there should be more, but this is a start.