It needs Packages, materials, PCB houses etc ideally all near by, with good transportation networks, etc. That was what ShenZhen was good at. It took very low cost labors and supported government and a lot time to build up.
Take a look at this video https://www.youtube.com/watch?v=leFuF-zoVzA on how to build IPhone from parts bought in ShenZhen public market to see the supported systems needed for HW. You can imagine how much easier and faster to prototype/build HW (drone, robots, etc) in ShenZhen as compare to anywhere else in the world (for now).
As the labor cost goes up in ShenZhen / China, the significant advantages are gone. That's why China is trying to move up via Tech/IP, etc.
Same development processes happened in Japan, Korea, Taiwan for the past 40-50 years. All of them start with unskilled Textile -> toy assembly -> Electonic PCB assembly -> PCB Design -> Simple Asic / Systems-> Complex ASIC / Complex Systems.
As they move up the food chain, they all "clone / steal / borrow / learn" ip from more developed nations.
It is also repeating the process 150 years ago where UK invented the Train/Rail system and US just scaled/improved to much bigger system.
History just keep repeating.