Has anyone's kid outgrown a 20" MTB? I'm looking for something resembling:

That's 20" wheels, single speed, coaster brake, rear pull brake. No training wheels.

My boy's ready for pedals and his little sisters are anxious to get onto his kick bike. That means I could use a second kick bike, preferably gender-neutral. This is what we have now:

If anyone has either, gently used, please reach out (PM?). I'm in North Andover, MA, so hopefully you're not terribly far.