(in the US) The one constant was that overwhelmingly older men and women were interested and impressed and had genuine questions or compliments without making jokes.
The younger you got with males, the more aggressive and posturing the questions and behavior. Younger females were non-memorable - mainly just looked or ignored. Pre-teen, kids of both genders are just curious.
There's a definite similarity in the behaviors of people as they get older and the very young in how they approach new and interesting things like a (e)unicycle. As people get older they seemed to lose all need to posture and prove themselves and they seemed more comfortable exposing the vulnerability of being curious and ignorant.
Men absolutely love to ask the cost.
Typically when people marvel at my wheel, I tell them if they give me a few bowling pins I can juggle as well.
When I first learned, I setup a couple large garbage bins several feet apart, and just tried to get from one to the other, using the bins to keep up / turn around / go back. As you improve, move the bins farther apart, and rinse / repeat until you’ve got it.
The electric felt a lot more dangerous to learn. I practiced going back and forth in a hallway (holding the wall), then practiced riding freely and turning in a parking lot, then started riding around my neighborhood.
It is dangerous, though. One wheel in contact with the ground, people don't know how to react to you, plus high speeds and poorly maintained roads mean a mistake by you or another person can mean a hospital trip with serious injuries. I think the risk is easily 10x or more than what it is to ride a bike around.
You generally have a fixed wheel on a unicycle. That would make derailleur gears harder to implement as they'd normally work with a freehub of some kind.
Hub gears like a Sturmey-Archer generally need to zero torque going through them to change gear. Again that's hard to do when you're using the forward and backward pedalling to balance.