For example, https://www.getcomet.net/galaxies/explore organizes some of its "planets" (like subreddits) into "galaxies" (categories). This isn't really a necessary feature but it would be a nice way to allow users to easily find new communities and maybe see some combined information about all of the communities in the category (number of posts, most recent post, etc.).

For the actual structure of it, communities probably wouldn't have to change any information about themselves and can instead just be added to a category by an admin (and maybe allowing a community to be under multiple categories). Maybe even having nested categories if that's feasible.

Not sure if this fits in with your idea of lotide but I thought it would be interesting and would allow for an instance to be a little bit more like a forum.