Lego was one of the best things I had as a kid, we didn't get sets back then as my parents couldn't afford it so we go second hand ones these days I build Lego Technic and am able to buy my own.
My nephew loves Lego too, and building together has been a lot of fun.
I'm not very practical with lego tecnics, I'm for the classic heh heh... but I fell in love with it as an adult, as a child I only had one but I didn't lose my mind 😅
In my opinion what you do with grandchildren is always fun 😉