I doubt your 10 y.o son (I have one also) could manage a 10" dob or even an 8. Either go for some binocs or get a 6" dob or (possibly better for balcony, not knowing the nature of yours) an EQ mounted newtonian or smaller refractor.
I would've loved something like this at 10! (From Bintel website):-
Skywatcher 80mm with Push Button Control https://www.bintelshop.com.au/Images/spacer.gif The Universe is at your fingertips with the Skywatcher 80mm Auto Tracking telescope.
A great choice for the budding astronomer - just as good for a balcony with a view.
Enjoy the wonderful images and simplicity of this compact yet powerful telescope.
ONLY $395 while stocks last!