If you want to export your products that are listed to a specific channel please follow the steps outlined below.
(This export file will also show the quantity that is listed to that channel.)
Please go to inventory-> inventory & listings-> manage listings-> active listings-> filter by channels-> select other actions-> export to CSV.
It can take between 20-30 minutes for your file to export.
You will be able to download a copy of your export file from the bulk actions section.
Inventory-> bulk actions-> bulk exports