My son just turned 4. He doesnt seem to mind using a keyboard occasionally, though searching for the keys leads to losing his interest quickly. He still finds it amusing typing words in a text editor and seeing them appear on the screen.

Touchscreen seems to be easiest be it for playing games or navigating youtube. He uses google voice quite a bit on an Android smart phone, since he found the "mic" button.

I have a 23-inch touch monitor hooked up to an intel nuc with Win10, which he seems to like a lot. Though the educational apps in windows store are very few. I was not able to find a way to hook up an Android variant to the touch monitor.

I have a 4 yr old. They adapt well.

My kid only used to be exposed to touch screens. Her daycare then introduced them to more traditional computers with a keyboard and mouse, and they adapted fine.