I'm willing to bet that you watche that Limbo spider procedural animation tutorial on youtube (if not then my mistake). Honestly, this is a genius use of the limbs!
I can't say that I've heard of that tutorial. I used Godot's built-in IK (inverse kinematics) and bone systems for the arm animations. Though it wouldn't surprise me if a spider animation would use a similar setup to move legs around.
