My daughter is 3 and learned to use a phone/tablet before she was 2. Whenever I'd pull up YouTube on my tv she'd walk to the tv and try to swipe it as well. Often getting upset thinking the tv was broken, haha.
She was used to iPads, but one day I gave her my Android tablet. She was upset at first because things are slightly different, but adjusted quickly. I was shocked at how fast she picked it up.
My 4 year old is just now learning to use a mouse, but she's been at a touchscreen for over 3 years.