> Never tried CouchDB though

CouchDB is a json document based noSql system that is exposed through traditional HTTP calls (e.g. GET to get a document, POST to create a new document, PUT to update a document, and DELETE to delete a document).

In the "expose data via REST" the stack is often "service doing SQL against a RDBMS" and that service is a either Java or Python or Ruby... that can often (not always) be done as "here is couch, with this data stored in it." It's memory and CPU footprint (even doing a 3x replication in our k8s environment) is a fraction of a Java container, much less a Java container and a database.

Grab a couchdb docker compose and spin it up and give it a try. It has a built in admin console. https://docs.couchdb.org/en/3.2.2/index.html