Every time someone comes up with an alternative to a software behemoth like Elasticsearch, what they actually mean is: "An alternative to the 10% of functionality of $tool that are interesting to me".

This is surely an impressive engineering feat, but hardly a replacement for the myriad of query possibilities Elasticsearch offers.

and almost all of them won't offer ES-compatible API. Out of my head i can think about manticore (https://manticoresearch.com/) that offers at least subset of elasticsearch API