I have a branded product that comes in a plastic bag (similar to Lays-style packaging or oats).
A random picture is attached, but the packaging is similar.
Since this is a food item, I would personally recommend to place it into some kind of outer wrapping or protective packaging. Buyers don’t like when labels are placed directly on the surface of the item, which damages the packaging.
This would fall under “Granular Products” category for Amazon FBA. In terms of prep requirements, if the outside packaging is durable enough (can pass the 3-foot drop test, vigorous shake test and would not easily tear during handling and transit), the item would need no prep (and no suffocation label). If the packaging is not sturdy enough and you decide to use a thick polybag for it, the polybag would certainly need a suffocation label.