I mean, even outside of Shenzhen, if you want bluetooth the NRF52832 has fantastic hardware layout/design documentation and a frickin' Cortex-M0+ processor for

I mean, even outside of Shenzhen, if you want bluetooth the NRF52832 has fantastic hardware layout/design documentation and a frickin' Cortex-M0+ processor for core logic and communicating with the BTLE stack. The ESP32 has wifi and bluetooth and has dealt with all that FCC crap (but uses a weird MCU core.) Etc, etc. Living next door to a few factories probably reduces your iteration times from weeks to days, but IMHO - and maybe this is the 'H' part, I'm still learning - the time that you as an individual wind up spending on design and figuring out software issues are pretty sizable, even compared to a fortnight for a nice 2-4 layer PCB. Either way, we are certainly living in a wonderful time for rapid prototyping. Dropping the 'IoT' tag, embedded systems are super super exciting in all kinds of areas; telecommunications are just one of those.