Meanwhile, to use such a motor does require an L3 certification - that process requires the L1 and L2 first - even on the cheap probably in the $2000 range.
We have a restricted area on this forum for motor making - you need to have your L2 certification and be a US citizen to gain access.
I’ll preface by saying what OP wants to do is incredibly dangerous, will be incredibly expensive and should NOT BE ATTEMPTED.
But use of the motor does not require any NAR or Tripoli certification in the US of A. OP can build his motor and find a suitable field and apply for an FAA waiver all without being NAR or Tripoli certified. He probably won’t get a waiver when the FAA hears what he wants to do. This still will not prevent him from being able to ground test the motor. So technically he could ‘use’ the motor.
Also the motor making forum here only requires an L1 and be a US citizen so OP won’t be able to.