Welcome to the Community, Cris!
The trick here is to use “Unpivot”. By unpivoting, we put the row data into two columns: field, and values. Then constructing fieldValues is trivial using the “Construct JSON” action.
See the example below:
construct-json.morph (4.5 KB)
For multiple rows, enumerate rows using the “Enumerate rows” action. Then use the row numbers for grouping in “Unpivot” and “Construct JSON”.