A problem many have realized is that there are many /tech, /gaming etc. communities in different instances/servers. There is already https://fediverse.observer/ , so I think it wouldn't be too hard to make a service that periodically roams the fediverse, checks for example the last 100,000 submissions of each (or top 100 active servers or something) server/instance, and gets info on all the communities/subs involved. Users could search communities, and if they write "gaming" they would get a list of all the active /gaming communities and info about them: subscriping users, total submissions, instance location (geographical) etc.
This could be used to find suitable /gaming communities for your needs.
A desireable future feature for both kbin and Lemmy would be to find and subscribe to multiple communities with the same name from the fediverse, and manage them to a single feed if the user so desires.
Ideas, thoughts?
I'm not sure, but I think https://lemmyverse.net/ is basically what you are talking about.
It lists both communities and instances.