Very cool idea!

but comparable or larger than probably any other city in continental Europe. Prague has a thriving local EA community, a newly established alignment research group, ~20 full-time people working in/with high-impact organizations (eg Metaculus, ESPR, ALLFED, CFAR), and about a hundred people in the broader EA and rationalist communities.

In case you (or anyone else) is curious about the size of EA communities in continental Europe: We did a quick headcount of FT EAs in Berlin and got to 30+. 

Thanks for the comment and further clarifying OP's point. This is an important perspective. I have edited the post to refer to your comment. 
Would you maybe like to share a link to some discussion regarding this for those who would like to read more about it?

Thanks, Niel, I probably should have been more explicit about this. I've added a paragraph to make this clearer.

Thanks. I don't have a personal opinion on this, but I've adapted the list to show which of the OpenAI positions were listed on the 80k job board and which not. I would point out that 80k lists OpenAI as an org they recommend.

Thanks!
AFAIA, the list of orgs is not linked to any official EA source, but a wiki that can be updated by anyone.  If you're looking for something more official, the list of organizations on 80k's job board might be better. But it's missing some orgs that are clearly EA-aligned, e.g., the national regranting orgs.