Feature Request: Filter & Sort by Availability

[JT68]

I know there isn't a dedicated feature request discussion, but I'd like to make a suggestion:

Product Availability should be a Filter & Sort option, and an option in Collections conditions.

Most of my product collections are automatic/all conditions,  like this: "Product Type is equal to ____ AND Inventory Stock is greater than 0". This prevents out of stock items from showing in collections. However, it also excludes the items where I have "Continue selling when out of stock" checked when the inventory for those items might is 0. I have certain items that are available for pre-order, or where the inventory is expected imminently. I would like customers to be able to go ahead and see/order those products. I do have custom Liquid code that shows a message if an item is out of stock and available for pre-order, so that customers know it isn't available for immediate shipping.