Intent:

To boldly know when viewing non-FBA (not fulfilled by Amazon) items

What it does:

runs when the page is loaded (works with product variation menu buttons)

checks for "Fulfilled by Amazon" or "Ships from and sold by Amazon.com" or "Sold by\nAmazon" text in page item-info sidebar

checks for out-of-stock/unavailable/unqualified/partial selection/early access/new or used open box accordion/etc. item-info

If not FBA, it puts a red frame around the page with a red text label and a red text label in the item-info sidebar.