Assuming what Ledger says is true and they use French pick & place soldering service, they only receive bare PCBs from China.
How would 'the Chinese' install a backdoor on a bare PCB? You know, this kind of stuff
Why would I trust anything that people from ledger are saying, when it's proven they are either liars or they don't know facts?
Backdoors are most likely hidden on microchips, not in PCB's, and it could similar like with smartphones that have encryption that can be decrypted by governemnts.
I don't understand they would invested bunch of money in making videos, music videos, promotional campaigns with celebrities, etc. but they keep hiding origin of their components.
Ledger is Made in China and Assembled in France, nothing wrong with that, just be transparent about it.