Using the REST API, the inventory_item_id doesn't have a mapping back to product or variant. The suggested approach would be to keep a local database of product and variant id mappings to inventory items if you want to identify your levels based on products instead.
Alternatively GraphQL has the ability to access both the product IDs and inventory IDs in the same call.
The webhooks you listed in your post are the ones that you would use to keep inventory numbers, specifically inventory_levels/update will fire any time the level changes on that item.
I encourage you to check our guide on updating inventory, and exploring GraphQL solutions as well.
Our review reference is 12897.
We have been been given some feedback points which we are working on, however we would like to clarify with the reviewer on one of the points that he/she has raised. How can we go about doing this?
Also the reviewer has added a 2FA authentication to the test account details that we have provided and as a result, we are unable to login to our own test account.
Appreciate your help!