Testing API data

  1. Is there a way to test API outputs in my project if it’s not used in the UI.
    For example in my Project I receive a color from an API but the color is just a value in the backend.
  2. After checking for API data, can I compare it by writing it in a table (API testing data vs. preset API data) then reading that table to see if it matches and return to testing script for a pass/fail status?
  3. Will any of the languages Appium supports be able to do this?
  4. Can this be performed on both iOS and Android?

API testing is best done with rest-assured.

Do you have any recommendations on how to access a variable from the app code? Just viewing it that way I can test against it.