https://www.robotshop.com/en/code--go-robot-mouse-activity-s...
It's a great introduction to programming. You have to put in all instructions on the mouse to solve the maze. There's also cards with instructions that you can place on the board to make it even easier.
We also bought an IoT kit from from https://littlebits.com/ when he got older that we started to work on together.
The key here is to do it at a 3-year old level and that you do it together, it's not about finding the right solution or not. Be open to your kid's creativity and don't just follow the instructions.
Also, Magna-Tiles! https://www.lakeshorelearning.com/products/blocks-manipulati...
We bought a starter kit (pretty expensive I know) but my son has been playing with it for at least 1-2hrs a day for a year. They are part of every game he plays, whether it's a car race or playing with dolls.