RAVPower, Vava, TaoTronics today – Aukey, MPow in May – these are all brands whose names I search for when buying electronics, because I've had mostly great experiences with their products. TIL they operate their own DTC sites (of course). Will give those a try next time.
I bought from Aukey directly and got a box from Amazon, so I went back to ordering from Amazon directly.
When I worked for an eBay seller ~5 years ago, we sold a lot of product on both eBay and Amazon Marketplace.
Given we often had inventory available in FBA (Fulfillment by Amazon) and not in our own warehouse, we often fulfilled eBay orders via FBA.
I've been out of the business for awhile, I think the rules around this from eBay's end have changed. Regardless, it's common for sellers to use 3PL (third-party warehousing and fulfillment) services, FBA or otherwise.