Once strapped to the treadmill its hard to grab for some stuff, that for I designed a magnetic holder for my pico 4 controllers. In addition to stay hydrated I also designed a 500ml swivel can holder that goes on the back where the original hook goes.
Of course I designed it in a way so the functionality of the hook is not gone, I even made it a double hook.
You can find the files on my printables page:
Magnetic quick controller mount:
https://www.printables.com/model/4715...
Swivel 500ml can holder mount:
https://www.printables.com/model/4705...