Hacker space in Seattle? Which one?

There's https://devhack.net/ in Seattle's U-District as well as Black Lodge Research https://www.blacklodgeresearch.org/ over in Redmond

They're both a far cry from what you're describing. But a lot of it is just putting the work in to build and foster a community around such a thing. Maintaining positive vibes among all members and making it a "third space" for those that want one

Devhack, actually didn't realize they had a site thank you! Definitely not super similar to what I'm describing but yeah inspiring nonetheless for sure.