Modern Apple laptops include multiple hardware encoders for H264 or HEVC. I think that Apple builds of TouchDesigner not supporting that is a bug.
Video Toolbox API provides hardware-accelerated video encoding and decoding capabilities on the Mac. For your reference:
- Complete example of a real-life project using Apple Video Toolbox hardware encoder (OBS, it’s open source), in C: obs-studio/plugins/mac-videotoolbox/encoder.c at master · obsproject/obs-studio · GitHub
- Sample code for “encoding video for live streaming” from Apple reference, which does the same but in Objective C: Encoding video for live streaming | Apple Developer Documentation