To be honest Temu sounds like someone was watching the Wish.com saga and decided it was a great idea to burn a bunch of billions. It can grow a lot while it's new but I have my doubts about longevity of this type "we only sell crap" platforms.
That said, I presume the only way Temu can pull this off logistically is air freight, so I also have my doubts about his sustainable this is.
A lot of stuff is dispatched from their local warehouses (or at least flown in from China and consolidated locally) and distributed by their own courier network.
Sounds similar to Temu, and TBH is probably exactly the same network. If you get tracking updates from "Fast Horse Express", it's definitely the same network. :)
There may be settled case law that says these aren't silencers legally, idk. The whole discipline is hilariously talmudic and full of the heap problem (is a billet of metal a gun? What about with one hole in it? Two holes and a chamfer here and a routed channel there? etc.)
The seller would need special ATF licensure and follow an onerous process to sell what is typically considered safety equipment in Europe, ironically. This involves submitting fingerprints, passport photos, and a lengthy (9+ month) approval process on the part of the ATF.
For the self-manufacture, this has been de-factor outlawed by the current regime with DIY kits being arbitrarily reclassified as suppressors themselves. Most if not all Form 1 builds are outright denied.
So, in short, Temu cannot sell these at all. Of course they also occasionally sell selector switches to concert Glock handguns to fully automatic. This is even more comically illegal than a suppressor workaround.
And yeah the Glock switch thing is absolutely wild. Sure, calling a shoelace a machine gun[0] stretches philosophy a fair bit. But the widespread availability of a bit of hardware that can only add select fire to a handgun tells me that enforcement is only a problem for those willing to adhere to the rules at all.