• That would be the question. You can certainly do a site search. At least duckduckgo can do that. It may not be so easy to just search lemmy, the threadiverse, or the fediverse for example. Do not know.

      • All search engines do this. You can append or prepend site:<domain name>.<tld> and it will filter by site.

        They even do wildcards, so to search any lemmy instance with “lemmy” in the domain name, you could do site:lemmy.*

        To include others, you can us an OR operator.

        So to include kbin.social you could use the following filter: site:lemmy.* OR site:kbin.social

        Unfortunately, this won’t work for instances that don’t have lemmy in the name.

    • Probably if the instances have lemmy in their domains like mine, or lemmy.ml, lemmy.ca, or in their name (mine is “pe1uca’s lemmy” so if the domain was different maybe search engines could also work with that), but not for ones like, lemmit.online, sh.itjust.works which don’t have lemmy neither in their names nor domain.
      It’d be like searching for content posted in sites which use wordpress.