It's not difficult to do wheels. They buy forgings precut and just use full size 20 years old CNC lathe and mill. Doesn't matter if most wheels made in few places - you need a very small shop of few guys to make them.
They start with copying design of others and then getting creative and competing for cost and weight. This ends up in almost no QC, cheapest blocks of unknown aluminum alloy without any test of material or forging class or quality. Since they are small, they can't buy from manufacturer directly, so they buy from agents who sell and resell everything and even they don't know what they sell. Suppliers of blocks also cheating them as well.
They will do few dimensions check on 1 wheel from the series and visual check, but most don't have anything more than simpler ruler let alone coordinate dimension scanner. They change design from the copy without even basic knowledge of mechanical stress and certainly without any stress simulation or any actual test. And they don't have engineering seniority to even eye ball it right.
Here is the catch - if this is high quality factory - they are big and NOT going to do small run production ever. And small shops not going to do anything except adjusting some numbers in parametric design and send to CNC. And you're dealing with small shops - one production supervisor, one part time junior guy who learned basics of Pro-E, one girl sales rep who can type and read basic english and 2 techs managing machines plus a warehouse operator. 50% margin, 30% profit. One owner who buys new apartment every 2 years and running few of different business like that.
There is another chance - dying mid size poor quality factory that can't find local buyers anymore and desperate to do direct sales for consumers in the west.
But you not going to know it. They can send you photos or address of somebody else factory. They can put temporary logo on somebody else factory when you visit them. Most of their sales reps are free agents who are paid commission only so doesn't matter how many of them, they sell for dozens of companies.
If eventually somebody going to die in the west due to their product they won't even know about it. No remorse. It was you who hit a pothole and died, not them.
Salaries of actual engineers and managers who can do decent production are same in China now as in US. And operators cost 5$/hour. And most business owners incredibly greedy and don't work for small profit margin. So if you get really good cost on custom product that can kill you - that's how you know it's stupid to do it.
P.S. If local guys have a brand for many years and very active in marketing that means they sold decent quantity and nobody yet died. I can't vouch for Signature Wheels. I believe it's medium danger - price allows decent product, manufacturing in Taiwan, quite long time on a market, active in marketing, used in actual race teams, weight is not incredibly low, hub doesn't look like a feather. This in my mind is a 100 times lower risk, while still 10 times worse than OEM or top brand.