Supply chain security is a known problem with mitigations. Don’t think all these billion dollar companies haven’t thought about the issue of having a third party implement their designs. Just like with software security, there’s no perfect solution but it’s highly unlikely China can easily bug devices sold in America without being detected. With software, you have cryptography to protect you. With hardware, you can buy chips not designed in China (which afaik is most chips). Even if the chip is manufactured in China, it’s not trivial to add in backdoor logic and have the design still work and not detectable by the designers (fabs are handed the equalivant of object code, not the source code).

All that aside I find issue with the thesis of your question. Assuming the Taiwan, South Korea, Japan are the same as China is naive at best and racist at worst. So asking about “phones not made in Asia” is meaningless (not to mention Asia also includes India, etc). Even if read by the spirit of the question and not the word of it, it feels very anti-globalist and protectionalistic which itself is not an issue but instead of repeating arguments against it, I’ll just refer you to the body of literature about the whole debate.