Astrobubu Meaning power the entire setup with one power brick.
You do not need to use a single power supply.
However, if you use multiple power supplies, you need to make sure the ground returns of the different power supplies are bonded together with either a ground braid, or at least some 18 AWG or thicker wires.
Essentially, you do not want the USB ground wire to become a ground return for the different power supplies.
I run a 13.8V system for everything (computer, cameras, dew heaters, etc) except the mount, and a separate 15V uninterruptible power supply (UPS) for the mount. I have a short ground wire that runs between the 13.8V system's ground and the 15V system's ground right at the base of the telescope mount.
Chen