Retrieve Printify Products - make update on google sheets - then upload changes to printify

Questions
1

I am needing to change my product descriptions for the 300 products i have in my store and trying to see if i change the description that i can only send that change to printify? I have a scenerior where i downloaded to my google sheets product name and description, used AI to regernate new description but cant figure out how to only send the change descriptions back to printifiy