Today Google bricked my Chromebook by force-installing a hidden extension

If the machine is less than 2 years old (and you are in eruope) just return it as defect.

laws should be adapted to extend the warranty every time a remote change is made to the device. basically, the warranty should hold as long as the device is maintained. say, each update should come with half a year of warranty. it's a bit tricky as it could motivate companies to stop updating, but that could be solved with a separate law forcing companies to provide an extra number of years to provide updates. (if that doesn't exist already)

This may make sense if the extended warranty is limited to defects introduced by the remote change. I.e., if they remotely break your device, they should be responsible for fixing the damage. A full warranty extension doesn't seem reasonable to me, though.

With regards to your last sentence, I think a good first step would be to require at least security and other critical updates to be provided within the full warranty period. And this would make sense even without the (limited) warranty extension, and I actually consider it more important.