Your link there kinda reenforced my point...more than your original point.
Your quotes...
"Brand stickers and specific boxes are used to market precisely the same item in many, many cases."
"because I know that, by and large, it's literally all the same. Brand stickers and specific boxes are used to market precisely the same item in many, many cases"
"there are very few actual manufacturers for these, and multiple brands use the same manufacturers."
...so the link you provided...shows a bit more than just a factory or three....with all brands simply slapping their own labels on the box and reselling under their logo.
BUT...that link you provided, is also missing many other manufacturers....it is not very accurate.
There is a linked article from that same page that I followed, which listed a lot of brands made in china itself...
This section provides an overview for solid state drives (ssd) as well as their applications and principles. Also, please take a look at the list of 9 solid state drive (ssd) manufacturers and their company rankings.
us.metoree.com
I'll offer a much longer list, from Wikipedia...
en.wikipedia.org
Now...some here (including myself)...will agree that the actual memory chips that are clustered on RAM and solid state drives....may be made by literally a small handful of factories (that I noted above..."mostly" Crucial, Samsung, and Hynix).
...however...solid state drive manufacturers....are rather flexible in their design, and quality...
I'm not about to spend a penny testing the quality of a "Fikwot" brand SSD, or "Ramsta" brand....hard pass here!