Just let her play games. All the Nintendo games are for kids. Croc, Dangerous Dave, Snow Bros, Super Mario. Google Games for Kids. I'm sure you'll find tons of it.

Also, let her play video games & then maybe later introduce her to Mac.

It would be best to keep 3-4 year olds away from screens as much as possible and given real toys to play with and colors and coloring books. :)

"as much as possible" - I do not think 0 computer time is good for 3-4 year old. For <=2 year old, sure, there should be 0 time.

I am thinking to start introducing her to computers and I prefer to start with Mac rather than phone/tablet, hence this question.

I have two kids, 4 and 7. They have a lot of trouble even typing basic things, it is pretty frustrating for everyone. If you absolutely must do something on the computer, I'd recommend something that teaches the basic skills of typing and moving the mouse around to start before getting into more advanced things. My kids, for example, seem to enjoy just typing in a word processor and seeing their name show up or writing down secret codes or whatever.

I also have list of things that they want to do / ask for, they like checking out that list and editing it.

Followup question. What are some good apps or toys for 3-4 yr old kids? Anything that can be used to teach about emotions?

It really depends on the child and what their interests are. In my experience open ended toys are better, like legos and wooden blocks, or sticks collected on nature walks. Avoid more linear toys.