I wouldn’t recommend this because by concatenating your data into one column, it will be more difficult to sort and query in the future. In addition you will have to store everything as a string separated by commas so to do any future calculations you would need to deal with this when you query.
However, if this is required for your use case all you have to do is define the column name in your collection and then on insert make sure to concatenate the data prior to the insert.
let newVal = val1 + "," + val2....etc etc.
"my_field": newVal
See the link for the full code snippet on how to inset values to a collection