Hi Sean,
The absolute easiest way to go about a slow-moving motor would be to get one with a gearbox attached. The closest speed I could find to your target in our store is 6RPM, but you could likely get away with one with less reduction (more speed) and drive it with a PWM signal or lower voltage in order to slow it down.
Using encoders and brushless motors will provide a truly silent experience, with excellent speed control, but such solutions are niche, and a little overpowered for what you’re looking to do I imagine:
Another option to consider would be stepper drivers with silent motor boards like the TMC2209, check out Geoff’s thread on his crane for his migration to silent step sticks:
I wrote half of this post a while ago, and only just came back to it, so there is likely more I wanted to recommend, but have a look at what I’ve recommended so far and get back with your thoughts 
-James
