Ooof!
Yea I know a guy years back who was always doing a hybrid confidence scam/tech accumulator business. He printed stock and traded it for cash, it was unbelievable how many years he lived well for running that scam.
Seriously, if you are producing in Senzjen where they can whip up a prototype in weeks why has nobody ever found a way to get a FOSS phone made. I bet it could be done between $10k-$100k especially if you walked in with gerbers or kicads ready to go.
(Yes I know you need to go through prototyping phases to test out the system especially the RF components)

To illustrate the idea of custom design just look ath those old real-fake N900s with DVB-T and could play J2ME games years ago. The thing is I feel like most of this Chinese stuff is a dirty cheap hack both hardware and software made in some dirty shop; it works, barely, no time for QC and falls apart like a house of cards if you try to do any normal hacking or customization over their fixes.