Any of these may actually be a dropshipper, but wholesalers are the most likely to offer it. The best source for dropshipping would be at the manufacturer level, because you will get the best prices, however most manufacturers know they can just sell their products to wholesalers without all the hassles of dropshipping, so it’s not easy to find manufacturers who will dropship.
You can also find retailers who will dropship, but you would have to charge more than they do to make a profit, and you won’t find as many buyers at those higher prices.
Most dropshippers will be pretty much invisible to the consumer. They will usually ship the products in your name, often with your logo and return address on the package, so it appears as though your company shipped the product to the customer.
Of course, you’ll have to deal with the occasional return, but in that case you’ll simply work with the dropshipper to make whatever corrections are necessary.