You can't get DRM "at the cell level". The batteries are just simple Panasonic 18650s, adding some DRM component to each and every one of them would be cost-inefficient and would also cause a huge problem if the chip fails during warranty.

The controllers are black boxes though, but you can get 3rd party units for Tesla batteries _today_. JerryRigEverything on Youtube built his own EV Hummvee on the military chassis using some Model X batteries and all 3rd party electronics.

It wasn't plug and play, but perfectly doable in a semi-well stocked home garage.