They have kits that allow you to quickly build really interesting things. For example, a Space Rover: https://littlebits.com/collections/invent-at-home/products/l... - scroll to the "What's In The Box" section and you'll immediately understand the price point. It's quite worth it. Educational through-and-through, yet everything is simplified by the magnetic connection strategy they employ to ensure you only ever connect modules in ways that work and don't ... fry. And the almost origami-meets-Lego build is a whole lot of fun.
We actually have the Space Rover Inventor Kit in our household, playing and re-configuring it a lot. The sensor modules and other plug-in things are really great. And you control everything using the tablet, which your nephew has already started becoming proficient at.
We love terrorizing our pets with it. But I digress....