The answer to that question in the US is within epsilon of “no” thanks to the cloud act.
Europe and China have passed similar laws. However, China has a reputation for passing laws then selectively enforcing them. Maybe if you get on the right side of the right party member, the answer might still be “Yes” there.
Anyway, the next question to ask is: Who would I rather backdoor my device?
I doubt the Chinese government cares much about me, and unless I vacation there it’s an international incident if they, say, hack my car and murder me by aiming it at a tree at 95mph, like the CIA apparently does now:
https://www.motor1.com/news/138679/wikileaks-claim-cia-hack-...
Of course, the US government banned cars from China. Presumably this is because they do not have the mandated remote murder network port open, or, if they do, the US doesn’t have the necessary permissions to access it.
Would Xiaomi or the CCP accept the reputational and legal risk of getting caught with a backdoor? Recall the CCP considered the arrest of the Huawei executive in Canada as an offense against itself.
For instance election tampering in the US is a well-documented thing: However it almost always favors republicans in districts with electronic voting machines that do not generate paper trails.
As for the person you are replying to, their claims have been documented by most media outlets, places like wikileaks, and their claims are backed by US legal requirements to backdoor stuff (like the US Cloud act).