To add availability of product through Wixpa feed follow these steps,
Click on View → Edit → scroll down to See Additional Product Data
In the 'Additional Details' section, you'll see the ‘Availability.’ Add the Availability and expiration dates according to your preferences, as I’ve done here.
Then click 'Save,' and you can view these changes in GMC by opening the product. You can also add Availability at the individual product level or for multiple products through bulk edit.
