[sailfast]

Simple stuff can be good for early "quantifying" activities. Hi Ho Cherry O is great for low number counting and subtraction from 10.

Uno is a good card game for order, addition (draw 2 + draw 2 + draw 4 is how many?).

Robot Turtles has been fun from a "let's try to discover what a function does" perspective but I'm not 100% sure what has registered yet. I found 4.5 yrs to be the sweet spot to start there.

The biggest thing though: time with your kid working on these things. If you're there, and you are engaged and having fun, it's likely they'll also be engaged and having fun. Start with anything. Keep it light. Let discovery happen without correcting. It's fun to watch.