Use an import mapping → https://docs.mendix.com/refguide/import-mappings/
You can map your JSON to local usable objects and use those in your microflows. I would recommend to create non-persistent entities, one for each in your JSON, to map them exactly as the JSON. Then from over there, map to locally usable entities (probably persistent, unless you don't need to store them in a database) with just the data (attributes) you need with a data-structure you require.
If your JSON is basically A → B → C, then your Non-persistent mapping should be A → B → C, but your locally used model can easily be just one single object, i.e. A, without B and C. That’s entirely up to you.
Thanks for your support!!