There is also https://www.search-lemmy.com/ which seems to work pretty well. It’s also open source

The future is here: https://www.search-lemmy.com/

As a matter of fact, I remember seeing this project posted about a bit ago: https://github.com/marsara9/lemmy-search

It can be selfhosted with docker or you can use the hosted version at: https://www.search-lemmy.com/

An announcement post is here: https://lemmy.world/post/963301