Just to finish my story: after deciding that I don’t actually need a cheap DSO, it occurred to me that I could actually use a cheap MSO (I had a Saleae logic analyzer on my wishlist anyways), so I ordered the unbranded MSO5202D from the seller Rosvola on Amazon. I got the same delivery estimate 4-26 December, but it arrived on Friday evening, shipped from within US. As the other poster, I also got a what seems to be a legit Hantek MSO5202D in original box with all accessories (including a registration card). It looks and seems to work fine. I don't have any other Hantek product to compare, though. For what is worth, the plastic looks OK too – as cheap-feeling as the one on my 10x+ more expensive Keysight DSO.
One awkward thing I noticed though is that the protective film on the LCD (the one placed by the LCD manufacturer, not by Hantek) was not removed before assembly, so the little red tab you are supposed to pull to remove the protective film off the screen is mostly under the bezel, hard to reach and impossible to pull. To remove the film, one would have to dismantle the oscilloscope. Not sure this is a Hantek thing, most likely whoever assembled it forgot to remove the film.