Downloading data from PRODCOM and COMEXT should be quite similar to downloading datasets from Eurostat database and implementing basic functionalities to download and handle these datasets should be straightforward. The datasets might be quite large however, making it perhaps useful to implement filtering on SDMX queries as well instead of downloading the whole dataset to your computer and filtering it there.
API base URL
API SDMX 2.1 - data filtering
Other datasets to consider: