I got my 2 year old grand nephew a Lionel O gage Thomas the Tank Engine set last year. It was one of the last ones that came with a ‘transformer’ instead of the hand held control.
He has had no problems operating it. Lionel did a good job on this set. Thomas does not go fast enough to derail, the whistle is not not disagreeable, and the set itself is tough to damage.
I just sent off a figure 8 expansion set to him for Christmas this year.