Does that still get registered that way if identical links/posts are cross posted instead of duplicated?

I regularly see duplicate rather than cross post, which is a shame.

I think Lemmy does set the canonical URLs correctly, always linking to the origin instance as canonical so it should see it as multiple ways to get to the same content.

Ultimately Google should figure it out if done correctly. But the problem remains that the userbase is tiny compared to Reddit, and mostly focused on the same relatively niche topics in the first place so it’s just not gonna rank very high unless you search for Linux stuff.