Need help for a "luffy arm"

[modern ibex]

I'm trying to create an extendable, articulated arm, similar to a tentacle, like Luffy's.
I managed to do it in Blender, but I can't recreate it in Unity.

My main problems are that I can't:

• disable the parental relationship of the scale, which means that if I scale a bone to fit it, it breaks the rest.

• make the ik chain constraint adapt to the new size of the arm, or change the root while in-game.

If you have any advice, I'd appreciate it.

Thanks in advance.