I live in the UK, but am from Norway. I know a few librarians though, and I know that community libraries are usually (or at least often) interested in projects that can connect their communities and help them with outreach. Something like this certainly could do that, and with libraries existing in most communities there is a built in network for broader proliferation there.

I’m also just very keen on the idea of libraries having a central role to play in the future of the broader fediverse ecosystem.

Edit: It may be key to pitch this to them not as a platform, but as a decentralised community network.

Loving this concept. May I make a suggestion? Show this to and discuss this with your local library. That strikes me as a good potential partner, and a model that can be replicated in most places to potentially help with everything from hosting to community resources access.