How to reduce surface friction when pushing a gear sideways in shaft direction

I’m thinking of a system where a gear engages and disengages by shifting it along the shaft axis. I want to use an arm/board from a servo to push the gear in and out of position, but I’m worried about the friction applied to the side face of the gear. How would I go about reducing/eliminating this? Is there a open side bearing, sort of like half lazy susan with hole in the middle? Do I have to design a custom bearing embedded into the arm?

Also, if I am to use dog clutch instead, how do you deal with friction between the clutch and the arm holding it?