Snake Rig

Foundation of the rig is to use IK Spline in inverse fashion.
Tongue is build up with Hair Follicles system (so very flexible).
Generally simply maya tools nothing fancy scripts or stuff like that.

Animations are retargeted from here (since the skeleton mostly matches): https://www.unrealengine.com/marketplace/en-US/product/animated-snakes-pbr-volume-01

A note during making this rig: Working with IK Spline you have to be aware that joints keep the same distance length between each other. So it's important to have a bigger amount of them.