@mhoye Do you want recommendations for your text-indexers question?
In the full text search department:
Take a look at melisearch (https://github.com/meilisearch/meilisearch)
or Apache solr (https://solr.apache.org/guide/solr/latest/index.html), which is like elastic search but without all the licensing kerfuffle
@mhoye ah, both of these are not what i would consider minimalist. Melisearch is smaller than solr, but especially solr has all the enterprise features of an enterprise java project from the 2000-ends.
Also, both run as a separate service that your application connects to, instead of being build into your application.
If you rather have something that is build into your application, maybe the full text search sqlite module is better suited. (https://www.sqlite.org/fts5.html)