You anyway hold no tech or IP of of your own.
The manufacturing will stay in China to cater a 1.3B declining population
The most expensive parts of a phone such as Processor, memory chip, camera lens and touchscreen are all made in either Japan, SK or Taiwan. Some other critical parts such as gyroscope come from Germany and other countries. If I remember correctly, even for China the IPhone indigenization percentage by value is around 20-25%. Until 2019, it was actually less than 10%. Only recently did China start manufacturing batteries, speakers etc for the IPhone which increased their percentage.
I hope at least in the next few years we can develop expertise in medium value components such as batteries and speakers.Now even though the percentage of Chinese components has increased. You can see, for most of the countries it is around 20%.
What is the threshold of value addition, for a country to be considered an iPhone manufacturers. The supplers are distributed accross the global & none of them have a majority stake (50% value addition) in iphone manufacturing.
Most ICs like DRAM, Flash, Processors, MEMS, camera module and even display which is semiconductor and battery cells are made in Taiwan, US, Japan or Korea.
These items are the crown jewels of those countries, and also make a large portion of the Bill-of-Materials cost of a phone and super spy like Chinese also has troubles stealing said tech, so at best they are limited to low end production of such items, like their ICs will use a larger technology node( SMIC of China theoretically can do 14nm chip production, their production in reality is 20nm and below, meanwhile you have TSMC at 5nm )
Displays bigger than 6.1 inch will always be supplied by Samsung or LG
The only state of the art Chinese production of this is of NAND Flash by Samsung in Xian and SK Hynix somewhere else in China.
What parts they add into their phones depends on what $$$ it's going to sell for, high-end phones with cutting edge specs will have higher percentage of imported components which are indeed state of the art, lower end phones will have greater chinesw contribution, like the screen may come from BOE displays which is a chinese vendor for example.
But even with low end phones they cannot fully supplant the Ebul Phoreners and go full Atmanirbhar Cheen, market forces and customer preferences discourage it, also the capabilities of their companies.