SQL is the C ABI of querying for sure. BI tools will never adapt to use Convex directly, and nor should they.
So... yes, Convex actually had a prototype SQL adapter for the read side of things back in the early few months when we were figuring things out. Convex's read semantics are very compatible with SQL.
We've kept this adapter on ice in part because of point #3 in the article -- we don't want to overpromise things which are a bad idea.
Meaning, if we exposed SQL on the thing as-is, this would presumably be for more analytical type queries involving patterns normal Convex queries can't express. Right now that would be a Bad Idea because your website would slow down just like every other database system allows you to.
So the current recommended practice is use our Airbyte Egress connector (https://airbyte.com/connectors/convex) and get yourself into an offline Clickhouse/MySQL/Snowflake whatever and jam SQL over there to your heart's content. That's basically what we do.
We may one day abstract this away by embedding some sort of mirrored column store sql thing (maybe DuckDB based? who knows) so you can do your analytical work without impact on your OLTP or integrating 3 more systems. But the team hasn't invested in that yet and probably won't for some time.