There are no fields in ACF that store comma separated strings.
You might be able to do this using 2 different “fields”. After import you could convert the comma separated string into another field type like a repeater, but there’s nothing in ACF that will do this for you.
https://www.advancedcustomfields.com/resources/acf-save_post/
https://www.advancedcustomfields.com/resources/acf-update_value/
https://www.advancedcustomfields.com/resources/update_field/
