Since communities are viewable by anyone without an account, including search engine crawlers, this is the case by default. It is then up to search engines to crawl them and rank the appropriately.
A major problem right now is that search engines down rank massively pages with duplicate content, and that's the case with most Lemmy instances because of federation. If the fediverse ever becomes large enough to matter, they will maybe change that, but currently finding things on the fediverse is not exactly a good time.
Edit: kagi search (paid search engine) has recently announced a "search on the fediverse" feature. Neat.
Duplicate content shouldn't be a problem as every post has a source URL. This is linked in the HTML head as the canonical URL. That way search engines know where something is from and that only that one is the true source.
Wow, does it? I tried it a while back and it was amazing but i saw no mention of Lemmy? Can you boost the entirety of Lemmy the same way you can boost one website?
Yes, Kagi has a bunch of “Lenses” not just for Lemmy & Kbin but for all kinds of sources.
As of right now I’m not sure how you could SEO boost Lemmy. The federation makes it seem like a single post exists on many different sites.
With nearly a thousand Lemmy instances it’s as though someone cross posted to hundreds of websites which there would be no way to prioritize with the way current mainstream search engines work.
They just need to program a method for indexing Lemmy, and the rest of the ActivityPub compatible services, as a single entity. I am sure they will catch up eventually.
Other comments are good answers. I would like to add that search engines including google appear to be struggling to index the entire lemmyverse because we generate more content that they process. With time, the priority we are given will increase until search engines figure out lemmy is top-quality content