Checking generated code for similarity against training set is possible, and is now done by both Copilot and CodeWhisperer. But it'll include code that just happens to be similar, even if that code had no influence on what the model generated.

I was finding the copilot trial was pretty good at reading something like an adjacent CSV file and building out a struct with proper data types from the data in it but beyond writing CSV->DB migration stuff I didn't really use it for a lot