I work with QuickBase and a few others. Data cleaning/import/export like you said are a big part of it but the larger aspect is client side JavaScript and working with whatever embedded language the platform has.

The other part is building custom apps that run alongside the no-code app, often backed by the API. I've implemented some fun things like transactions that lock so you don't have simultaneous write problems and full text search.

If you are in that business, the distinguishing features that I would look for is being able to use the relational model, an API or way to run code, and regulatory compliance (HIPAA, FERPA, 21 CFR Part 11). Native transactions would be a miracle (for instance update a record and associated child records and roll back if validation fails).