Mhhh, I can’t find what the actual import duties are. The closest I found was this article https://www.whatcar.com/news/chinese-car-tariffs-will-not-go-ahead-uk-government-confirms/n27198 that suggest there is none (unlike in the EU, where the rate is 35%).

BYD sell the dolphin for about 10k in China. So they could lower the price a lot more, and the current price reflects more strategy and marketing than production and import duties

ARM is a UK company that sells more CPUs than Intel and AMD combined. They dominate the mobile market. Literally all phone chips use ARM technology. Their GPUs are not bad for tablets and phones.

They been trying to get their CPUs onto the desktop and server markets for years, and they are beginning to get some success stories on both.