Ok, other people are jumping in, so I guess I will too. First off, have you checked out the thinkgeek.com website? Tons of great ideas there, for geeks of all ages.
I wonder if anyone I’ve gifted starter tools still has them. I like to give a partial set for fourth birthdays—level (yes, there is an app in your phone that does that, but I mean the kind with the bubble in it), electric screwdriver, which they play with like it’s a drill and also enjoy using properly, and a tape measure, which is often the focus of a stage around that age. A rubber mallet, depending on budget. But I’m just daydreaming about little ones, smaller than yours.
Geek favorites that involve no tech are the board games Settlers of Catan and Munchkin.
You can get high tech fancy drones for a lot of money, or remote controlled helicopters for under $20. I think ball helicopters are really cool. They are shaped like a ball with propellers on top, and are controlled via hand movements instead with a controller. This looks fun; if they have phones they can use https://www.uncommongoods.com/.....r-airplane
The programmable Lego technics kits with motors start around $100.
You mentioned that your husband likes to give iPad type devices. Those would certainly be happily received by the kids, but you have to coordinate with the parents.
If you look back at my post about tech for my dad, you’ll see numerous watch-type devices that have gis, so the parents can track the kid. Some have other cool functions.
I got my kid a pair of those windshield wiper glasses around that age—he couldn’t wait for rain.
