In the Shopify interface, I can manage product availability (Online, Messenger, Facebook, Instagram).
I want to update these availability with REST API(only one or all). Is it possible to do this ?
When I change this option and retrieve product, there is no difference between the 2 files.
Haven't tried it myself but I think You're looking for Sales Channels:
This post suggest that it's not possible to change to all channels, but keep searching for sales channels api: