While this might be an alternative for that one specific use case (search bar), it does not feel like a viable alternative to ES. I am sure it is great at that specific case, and don't want to knock them on that. But, I have never used ES for a simple search like they are. when I use ES, I want to store billions of records redundantly and search them by text, time, and/or location. And then create visualizations with the results.

When I first read the title I thought it might be a Rust based Lucene engine or something, and thought that would be pretty cool. Though no idea how that would work. On its own, this is a pretty nifty little tool, however I think the framing as an ES alternative is what feels wrong to me, and apparently others in the comments as well.