Just now realizing that not all the posts are showing up on this instance. I might be the only seeing this, or maybe I haven't configured the federation settings properly? Does anyone know how I could get everything to sync?

EDIT: They are now showing up for me (We are federated y'all!)

The 4k ones are all in the community

Yes. Right now, it's listed in the posting guidelines: https://lemmy.opensupply.space/post/1

But I suppose I'll have to enforce it.

I'm a little hesitant to post the spreadsheet, since most top-tier providers don't want their information posted publicly. I reached out to each provider to ask them if they would be willing to have their service listed, what you see in the community are the providers who are comfortable posting publicly. A few more (about 6) will be posting soon, the rest have really poor quality (you can find these guys on the first page of google) and have been rejected from the community.

The community also allows providers to post updates, subscribers can discuss and give feedback, which in turn helps other folks. I think building a good quality repository of community contributions will pay off long term.

Personally, I would prefer element or signal, as suggested in the posting guidelines: https://lemmy.opensupply.space/post/1

But most of the providers have been operating on discord/telegram for a while and are unwilling to make the shift. They have their reasons too, I guess.

I understand why you think that might be the case, but I've set up the community such that you can't create a post unless you are approved by an admin. Approval here means that your service needs to be vetted before you can post. The whole point is to find quality providers and share reviews, if we allow anyone to post, the community would be overrun by low effort spammers in no time.

Also, see this comment on why I'm hesitant to share the spreadsheet.