If you run ethernet cable, you are actually running 4 good quality twisted pairs.

You can reuse pairs from Cat5/6 cable for CAN, or RS485 or PJDL or whatever. The same cable could carry 4 such buses (so you could have all of them in the same cable run). Try to use pairs that are twisted in the cable (for eg blue / striped blue)

Off topic, but "for eg" is like saying "ATM Machine"; "e.g." already means "for example": https://simple.wikipedia.org/wiki/Exempli_gratia

Yes I did so in my setup I have used CAT5 in star configuration all inserted in wall ducts alongside power cables. I can see some AC interference induced but pull-down resistors are able to erase that completely. I have dedicated 3 wires for the power supply +9v, 3 for ground and 1 for communication.

Yea but I need all 4 pairs for gigabit and the other upside for CAN is that it actually works in a ring topology. I'd probably run a cheap cat3 cable.