Some people reported they did it successfully after battery firmware being updated, there is even video on youtube where Mavic Mini user replaced stock cells with Sony 3000mAh ones and did then hover testing.
In comments he confirmed Drone and battery both were updated just upon unboxing (otherwise it was not possible to take-off).
It is not possible to take off without the mini being updated this is true.
I'm just telling you my experience. I sacrificed 6 batteries. I tried live swaps and everything without success. Just be warned before you try. Maybe when doing the live swap all batteries need to be the same volt. I don't know.