One of the best things about reddit was looking for answers or other users with the same problem as you, and since Google didn’t really help with that anymore and instead insisted on giving you business results, the best practice was to put your search terms in followed by ‘reddit’ and you’d find your answer.
I think OP is asking about a broader, Fediverse-scaled search. So using the
site:search tag will only search a single Lemmy instance. I don’t think Google will index cross-instance content in those searches, otherwise it’ll end up with a ton of duplicate results. So if what you’re looking for was actually posted to a different instance, it may not be found with that search.I’m just theorizing, though, since this is all still really new and untested.