I bought the Infinity 76 for one nephew at about your son's age, and he enjoyed it but grew out of it pretty quickly, and it is quite limited, because it doesn't allow you to use 'any' eyepiece.
For another set of nephews we bought a Celestron Travel Scope 70, which comes with a lightweight camera-type tripod, so it'll take a bit more supervision initially, but in a year or so he'll be able to set it up and use it himself.
It also works well as a terrestrial telescope (it has a prism to give an upright view), so can be used for bird watching (albeit with a fairly narrow field of view) or for looking for pirates.
Supplied with its own travel rucksack, it is very transportable, and it can be used with better quality eyepieces, if you want to upgrade with an eye to the future. It has to be said that the tripod is very lightweight and hence wobbly, but it can be replaced (or stood on a table at its lowest setting).
If you are interested yourself, this telescope on Gumtree is very well priced and in the London area.https://www.gumtree.com/p/telescopes/sk ... 1317613325