I don't trust that myself; I'm just saying, if we assume it's actually assembled in France, and they only get bare PCBs from China, the devices can't have 'Chinese backdoors' on them. Except if they buy backdoored components of course, but as you said, everyone gets their components from China.
If we start getting paranoid about everything that can have Chinese backdoors, we shouldn't buy 90% of the things we own. That includes the monitor you will read this post on, the mouse you open the thread with, and the chair you are sitting in.
All companies lie to protect their business interests and to increase their profits. When they get caught, they will lie about why they were lying. Even when they are not lying, they are intentionally withholding the truth or parts of the truth from their users to protect themselves and their profit margins. And yes, that goes for Ledger's biggest competitor as well.