My twin boys have just turned 7. We got them a switch lite each (second hand - eBay). We thought about one switch between them with the controllers but think it would have been arguing.
With games, if you have the ones with the controllers they both can play on one switch and it connects to the tv. If not then you may find they both need the game. We have found that Mario Karts, Minecraft we need to buy another copy. Will put them on their Christmas list. X