Is there a way to search through posts across all instances/communities?

Hi, I'm relatively new here. Like probably a lot of people, I appended the word "reddit" to most of my searches to get discussions around my interests/news or to find "curated" things. I noticed that it does not work as great with "Lemmy" for example, as the user base is more spread out and smaller in general.

• I've looked for a search engine for the Lemmy or fediverse with no luck. There exists some to find communities but not to return posts it seems.
• If it does not exists, is this even something that can be built? Would one need to build a crawler or use an API? I would be very interested to contribute to such a project.