I forget if we answered this question yet. My question has changed a little. Is now a good time to start opening tracking issues in each of related NoSQL projects that map to databases supported by
https://github.com/eclipse/jnosql-databases?
My personal experience was at a commercial database (Model 204) vendor (a few years ago :-) when we met with a local SQL Access Group representative that explained the problem they were solving by creating a common (SQL) call level interface and embedded SQL interface. We adopted the standard and we gave a lot of feedback for the early releases. The call level interface became a standard initially when Microsoft based ODBC on it and later JDBC was also introduced. This all happened over many years. I think that Model 204 + Informix were the first vendors to actively support the call level interface (Model 204 also implemented the embedded SQL interface for Cobol) but it really took off when Microsoft + Sun created their own standards based on the CLI.
Regards,
Scott