This is a self-plug but shapedata.io does similar things on top of Postgres -- it is much younger than Datasette, so has far fewer features, but should give you a similar exploration experience!
I downloaded and parsed through 100M prices negotiated by Blue Cross of Washington (Premera Blue Cross) for all their in-network healthcare procedures. I've compressed about 5TB of JSON data into much easier to work with tables that you can explore yourself. Excited to hear about what you find!
You should be able to build every SQL query with this. I built an example Top-N query here: https://imgur.com/a/2xKLltl
Right now building Top-N (and my example) assumes you know the rank function exists, but over time it should be easy enough to pre-build "nodes" that do things like this automatically :)