Learn 3D modelling. It's hard to say what future interfaces will look like, but you should definitely learn the asset creation pipeline.
I've been using Blender for close to a decade now and cannot recommend it more. If you spend a few hours a week practicing your 3D modelling, you will be well-poised to start creating content when VR/AR adoption kicks off. Another safe bet is WebXR, which Apple has more-or-less confirmed support for (alongside Meta).