I tread the same path of animator to Technical animator.
skin weighting, rigging, python, and Maya.
Skinning: understanding how to paint skin weights efficiently and realistically, knowing what edge flow does to deformations, and understanding how to control the number of influences on a vertex.
Rigging: Understanding how joints/bones/deformers work. Knowing the best joint placement within a mesh for optimal deformation. In Maya, understanding the joint orient attribute and how it relates to flipping and gimbal lock. IK , spline IK, and ribbon IK setups. For games, understanding how to separate the exportable hierarchy form the control rig.
Python: Plan for doing the same tasks over and over again. Rigs are never ‘one and done’ they will be constantly rebuilt and iterated on. Changes in the mesh will come at a moments notice, animators will request new features, so consider your rigs a “live” thing that will be constantly rebuilt. Scripting python will help you build tools to quickly iterate: saving/ transferring skin weights, modular procedural rigging systems, and utilities to speed up common tasks.
My general learning process was : figure out how to rig a thing, then figure out how to script that rigging.
Some Tech Anim jobs seek people to handle the engine side of things. So understanding animations are connected to skinned mesh assets is important, and animation trees like Unity’s Mecanim or Unreal’s State Machine and how they blend between animations. Invest some time learning how animation is processed in the real time code. See if you can script a peek at the curve data. See if you can pass custom attributes from Maya into the engine. See what happens with joint scaling. A general understanding of linear algebra (vector and matrix math) is also useful.
For demo reel stuff it’s good to describe the specific problem you are solving and show the final in-game result: Rigging Demo: Doctor Octopus - YouTube
It’s a job of constant learning, so stay curious.