Hello 🙂
I would first model the tongue going straight,
then I would create one curve along the tongue, and another one shaped like the end position of the tongue.
then I would rebuild the curves to have the same vertices number.
then I would do a blend shape to make the straight curve match the end pose curve.
Then I would duplicate the tongue geo and placed the duplicate a bit aside.
I would create an unroll animation onto the duplicated geo (easily doable with a simple bend deformer).
then I would create a blendShape selecting first the duplicate and then the main geometry, in order to transfer the unroll animation to it. (setting the weight to 1)
last I would create a wire deformer to deform the main geometry with the straight curve.
last but not least, I would set the straight curve blendshape weight to 1 so that the straight curve matches the final pose.
Thanks to the wire deformer, the tongue is now in the last pose position, and you can animate the bend Deformer
to unroll the tongue.