Being welcoming to every random person is by definition not a community, it's a free-for-all mess.
A community means communal interests and values, it's in the name. And to guard those you can't just be accepting everyone without vetoing them. That's how it turns to a shit of spammers and trolls and people who want to hijack it and don't share the original cause/spirit. Has happened to forum after forum...
In the end, you need to filter people at the door. You need to keep unpleasant people out and shut down bad behaviour.
I figured that a paid, motivated moderator could be better than a web of trust for this demographic. Maybe enforce a stricter moderation standard on unvetted members. At my scale it might work.
Or have a two-stage process: run very public, very open events that anyone can sign up to an attend. And then invite specific people that you meet at those events that look like a good fit for your community to your private, community-only event.
The closest analog I can think of is community-run bike repair workshops. Some people are deeply involved in, and others just have a flat tire.
The closest digital equivalent is the forums of old.
This preserves anonymity because for the latter because they’re only known to be “related” to the former, which is a vague hint at their real identity (e.g. they could’ve met in another online community). And the former don’t care, if they want they can vouch an anonymous alt.
Spot the fed