how about one of these DIY STEM kits for kids
https://thestempedia.com/setup-robotics-lab-for-school-with-structured-curriculum-diy-robotics-kits-and-practical-activity-books/?gad_source=1&gad_campaignid=22236459034&gclid=Cj0KCQjwmK_CBhCEARIsAMKwcD6UJs6GefJmwIzCtLVP7Jf3QHPDK4OQpkd1t7cFXCAJKGUcF4nSAAoaAvoPEALw_wcB

i haven't tried them, but they're on the radar

bit pricy, but might have to try an aliexpress version

these unofficial 3d minecraft cubes are also good