The issue isn’t instances.
The issue is that Lemmy isn’t designed for interaction with single actors, e.g. Mastodon users or PeerTube channels. Lemmy can only interact with groups, and that’s by design because it’s a purist Reddit/Hacker News clone.
If you have one account someplace that isn’t Lemmy or Mbin (or something similarly specialised), you can connect to and interact with just about everything everywhere.
Just because they know the Fediverse, doesn’t mean they know Lemmy.
For more than 50% of all Mastodon users (that’s more than 25% of all Fediverse users), the Fediverse equals Mastodon. For large parts of the rest, if it doesn’t behave like Mastodon, it’s disturbing.
Besides, how are they supposed to learn about Lemmy anyway? Yes, in theory, Mastodon and Lemmy are federated. In theory.
In fact, however, they’re almost completely incompatible. Lemmy is all about groups. It doesn’t support any interaction between users directly. Mastodon, on the other hand, is about users interacting with each other directly. It has no support for groups whatsoever. At all. Nada. Zilch.
One of many reasons why there’s almost no interaction between Mastodon and Lemmy that’d demonstrate to Mastodon users that Lemmy exists by confronting them with Lemmy content.
By the way, the latter won’t work anyway. Mastodon doesn’t show you what software a message came from. Thus, most Mastodon users assume that everything they see comes from Mastodon.
Mastodon. Hands down.
Mastodon has more monthly active users than the entire rest of the Fediverse combined. There are lots of people for whom the Fediverse equals Mastodon. Most of the time, when someone hears about the Fediverse for the first time, it’s explained to them as only Mastodon, allegedly because that’s easier to understand. And there are vastly more people who have heard of Mastodon, but not the Fediverse, than who have heard of any other Fediverse software, but not the Fediverse.
There are tons of phone apps made for Mastodon and only Mastodon. There are websites that have “Fedi” in their name, but that are built hard against only Mastodon, and if they’re compatible with anything else, it’s by chance. diaspora* (remember 2010 when those four kids announced a free, open-source, decentralised “Facebook killer”, asked for $12,000 of crowdfunding and got over $200,000) refuses to join the Fediverse because, according to one dev, Fediverse developers don’t “implement ActivityPub”, they “implement Mastodon”.
Lots of people say that claiming that Mastodon is the Fediverse is justified.
Here are the numbers from the FediIndex:
It’s the most powerful and feature-rich Fediverse server application ever, hands down. Also because it has features implemented that go vastly beyond what ActivityPub is capable of.
It was made by Friendica’s own creator by first forking Friendica twice over in 2011, then completely re-writing the second fork in 2012 and then expanding the re-written second fork in 2015.
While it was the first application to ever implement ActivityPub (July, 2017; two months before Mastodon), it has always been based on its own protocol, Zot, that was invented by Hubzilla’s own creator in 2011.
It’s Friendica, much more modular, with nomadic identity, with a staggering permissions system, expanded into a full-blown “social content management system” with all bells and whistles.
It’s basically Facebook meets WordPress meets Nextcloud meets a whole lot of other things.
Features:
Friendica has only got four advantages over Hubzilla. One, it supports the Mastodon client API (although that’s half-useless because Mastodon apps don’t even cover 20% of Friendica’s features). Two, it has mobile apps of its own, although stable releases only exist for Android; on Hubzilla, there’s only the Web UI for everyone anywhere. Three, it has even more connection options like being able to integrate a Bluesky account and “remote-control” it. Four, it’s easier to use; this is also because Hubzilla is highly modular with tons of optional, off-by-default stuff whereas just about everything is hard-coded to permanently on on Friendica.
Otherwise, Friendica is no real match for Hubzilla, and Bonfire is even less of a match.
You may also want to support groups on Hubzilla, (streams) and Forte.
Fair warnings ahead: First of all, there is no central index for them whatsoever. You’ll probably have to find a way to crawl them.
Also, crawling anything on (streams) is difficult. It officially and intentionally does not have a name (not even kidding here). It’s the only Fediverse server application that doesn’t even come with a default server identifier. A Lemmy server always identifies as “lemmy”. A (streams) server rarely identifies as “streams”, only when the admin explicitly and intentionally makes it identify as “streams”. Otherwise, it has identifiers all over the place, usually automatically derived from the server name.
What makes crawling (streams) even harder is that almost all nodeinfo code has been removed from (streams) on purpose. It’s also being kept away from all Fediverse stats and listing pages like The Federation, Fediverse Observer, FediDB and FediIndex on purpose.
Forte does have an official name and branding. However, AFAIK Forte still offers the possibility to change the server identifier to something else than “forte”. Also, while it does have nodeinfo, Forte’s nodeinfo doesn’t send any stats AFAIK, only zeroes for everything.