How do I give my product feed to Facebook and Instagram using Sales Channels?

Use the Meta card on Plugins → Sales Channels:

1. Click Connect on the Meta card (or tick Enabled if you connected it before). This creates its feed.
2. Click Copy next to Feed URL.
3. In Meta Commerce Manager, go to Catalogue → Data sources and add a scheduled feed using that URL.

The Meta feed has its own address and token, separate from Google's. If the URL shows only a path without your domain, your store's live website address is not set yet, so put your store domain in front of it. Use Settings on the card to choose whether out-of-stock products are included.