If anyone has problems getting their tyres on or off with tubeless rims, I think I have finally mastered it.
The trick is to get both sides (beads) of the tyre deep into the centre of the rim, that allows for more movement of the tyre on the rim and should leave enough gap to get the tyre on or off with just a little force on the tyre lever.
I have found on my gravel bike tyres that the tyres may not sit right on the rim after using the above technique, I simple inflate them to a much higher pressure and they generally pop into the right position.
Not sure if this is what you should do but it works for me.