With steampipe you can standardised the interrogation of multiple API into a SQL format. In most of the cases that steampipe delivers on today that is focused on cloud services/application with some limited endpoint level querying.
If there was a fleet plugin to steampipe you could easily generate one query that joins both Endpoint and cloud data as needed. This is slightly different to the two Cloud Query concepts that we've had in the OSquery community as it's mainly live query which oddly enough is the basis of why OSquery is so successful.
My goal was to build a FleetDM plugin that connects to one or more fleet instances and subsequently to endpoints so that I could query OSquery tables and join the data with cloud app data that OSquery already had like AWS, VT, etc.
Steampipe also supports non query APIs by translating them to Insert, Update, Create style endpoints which would mean you could provision configs on fleet, or add users, etc all through a simplified SQL language