NIP 29 invite codes or NIP 43 invite codes? Anyhow, I guess that's besides the point, it looks like I can read ok from the relay, except that filters that include any group-related kinds get blocked

I imagine it will be difficult to convey a lot of that information through clients, with different ones supporting different features. Maybe the landing page could utilize a secondary description box, so the root user can point back to it from the short description that appears in clients? "Look here for instructions and a list of what we do" type of thing. If the owner wants their things to grow, they'd need to make it clear & enticing enough to follow links and read, but that is kinda how everything works anyway, right?