feels, did these kinds of communities before centralization, im pretty physed to run a topical instance. find a small server and make a spot you can put your links for now, eventually there will be community aggregators
There's already browse.feddit.de if that's what you mean by community aggregator. On my instance one of the things I'm experimenting with is a simple bot that auto-subscribes to popular communities on different servers. It seems like the easiest way to populate a small community instance that intends to browse and not just communicate amongst themselves, almost like the "default subreddits" back on Reddit.
Where do you copy and paste it to though? If i copy, for example, the first one listed, Announcements, then go back to lemmy.world and paste it into the community search, it comes up as !announcements@lemmy.ml, and the searrch comes up blank. If I manually type just "announcements" and search, I get results, but that's what I'm already doing.
And return to being back on your own instance (Lemmy.world it seems) and are logged in.
In your main menu there is a small search icon, tap that and enter the address like above and hit search. It can take some time to appear these days, but eventually the community link will show up, maybe at the bottom under posts that included it.
This hit sidebar, and then can find join and comment
Personally, I'm planning to try and integrate that lemmy explorer directly into our instance to do this automatically, but there's some changes I think I want to make first regarding how lemmy works.