I’m running a standalone Lemmy instance, but I’m not planning to develop or grow a community on said instance since it’s mostly to practice my infra and DevOps skills. I would, however, like to subscribe to all communities on other instances, for example, on lemmy.world and several others. Is there an easy way, or can I only subscribe to each community individually?
You can only subscribe to communities individually, and as of this current moment, there is nothing like the “relays” that other Fediverse platforms have to push known instances to your own instance.
The way federation works is that an instance must explicitly search for an ActivityPub compatible instance and then start requesting data from it, there are no central locations that will provide an instance with all of the known Fediverse.