We don't feel acceleration when we are only in a gravitational field due to equivalence principle as I understand it says gravity is simply inertia in spacetime. Is there any other type of force where one would not feel inertia , for example diamagnetic levitation?
Yes, If we can generate a force that accelerates each and every particle of our body equally in same direction. There are two extremes -
No force at all (in far space) - This means equal (0) force/acceleration on each and every particle of the body, and we do not feel that acceleration/inertia. Standing on earth we feel the gravitational acceleration because the EM force on our feet is different from that on rest of the body.
Spagettification in gravitation field of a black hole. That is where we feel acceleration even in a gravitational free fall because it starts to vary so much across the body. That will be a very different kind of acceleration feeling as compared to what we are used to on earth.
In Practicality, an ordinary gravitational field is the only one capable of providing equal acceleration to each and every particle of the body. Examples of scenarios inside an ordinary gravitational field are - A free falling elevator, being in an orbit, or an airplane changing its altitude can produce an acceleration on a human body lasting several seconds or longer.