Both the alternatives you described have serious drawbacks.
John Ormerod, a leading magnet expert is less than impressed with FeN magnet developments.
I follow him on
https://www.linkedin.com/in/jormerod/recent-activity/all/ .
None in the field are providing adequate performance data and apparently the manufacture is very difficult. (Nitrides are inherently unstable in the presence of oxygen.)
Ormerod quote: "Will someone at Niron Magnetics, Inc. please define what "High Performance" means....a simple 2nd quadrant demagnetization curve will suffice."
In the matter of Induction motors I'd agree a loss of a couple of % efficiency won't really affect the need for battery capacity. But it doubles the heat generated inside the motor and we know EV magnet motors need to operate well beyond 100c. So cooling systems for an induction motor will add extra weight and expense.
Neither is a preferred option anytime soon.
(20min delay)