That’s not really how GPUs work. Nvidia/AMD aren’t “just a factory” you can't replace them like that, they are primarily design and software ecosystems. The silicon is mostly manufactured in Taiwan (by TSMC) because advanced GPUs need insane yield control, and that isn’t something a shitty Chinese factory can spin up.
Even if China can assemble a “local” graphics card, matching Nvidia/AMD is more than making a chip that powers on: you need an ecosystem. That’s why “just taking over and making GPUs” isn’t realistic it’s years of R&D, patents, tooling, and software drivers, not just manufacturing.