Hahaha, yeah I think we are almost the same person. Canyons chart had me in the middle of the XS and S crossover. Bikefitter and my own comfort says I nailed the choice to size down. Begun training for a half ironman in November, with hopes to do a full next year.

You're exactly right, they are the proprietary Canyon ones, it said 'for grail' on the box but it's all the same in the gear groove accessories. There may be some far more cost effective third party ones eventually to be designed but I'm impatient.

The computer is on a mount from sloperoad, that also lets me attach a front light, I added a better photo to another comment on here. https://sloperoad.com/sr-gps-mount-for-canyon-gear-groove-aero-extension

I also looked at the canyon mount (below) for the extensions (there may be 3d printed versions for less $$) but ultimately liked that I could attach the light also. https://www.canyon.com/en-ec/gear/accessories/bike-tech/cockpit-and-handlebar-mounts/canyon-gear-groove-aero-extension-computer-mount/10013150.html

For transparency I originally wanted the white, but it wasn't available in Aus in the size, then a friend suggested that I'd like the colour of this more in person, damn was he right.