Regarding potential warranty issues, the onus is on the manufacturer to show that any accessory has caused the particular warranty problem, not the other way around. Fitting a power frunk or boot kit shouldn't normally create any significant warranty issues, but clearly if it taps into the CANbus and that causes other faults to appear then that would be a good reason for Tesla to refuse a warranty claim.
Same goes if the motorised rams damage the boot seal, or if they overload the circuit they are connected to, Tesla wouldn't entertain a warranty claim for such damage. If something went wrong that was unconnected with any modification to the car, then Tesla would still have to honour the warranty - they cannot refuse unless they can show that a modification caused the problem in question.
My view is that fitting the power frunk/boot kit is pretty low risk, as long as neither tap into the CANbus, and as long as the electrical installation is done to a safe standard.