The average person dont like linux, and if they buy a linux laptop the reason is because its cheaper than the windows one. So why manufacturers still use unknown distros (like lenovo with endlessos) and not something like ubuntu or mint?
if the manufacturer of the device itself isnt trustworthy everything you do to try and make the device "trustworthy" is futile because OEMs could not just implement backdoors at the software level, but firmware or even hardware level.