Korean and western made stuff guarantee to have such thing. CNC devices in Russia stopped working. Even NVIDIA gpu has back door according to China and NVIDIA had to settle this matter behind the scene with China government. At this point, your phone is 100% backdoorable by western government. The only thing protect you is you are non-threat and too small to be bother with.

Is there documentation that GrapheneOS Pixels or iPhones are backdoored by governments to the extent that any person can be targeted?