Reddit mentions of Hello App Inventor!: Android programming for kids and the rest of us

TinkerCAD is also cool, has more than just block coding resources (electrical engineering, computer-aided design, etc.).

Try out GameJams (using game development software like Godot or Unity), too. That might get them to learn to love how fun and cool coding can be rather than just the idea of coding.

MIT AppInventor2 might be good for the older kid, after he/she has had some experience with scratch and the other resources that have been recommended.

If it were regular school, I'd say the older kid should take a "scratch course" one year and then the next take the "MIT AppInventor 2" course.

Useful books for MITAppInventor2 (these were used in my community college intro to computer science class):

• "Hello App Inventor!: Android Programming for kids and the rest of us." by Paula Beer and Carl Simmons
  
• "Building Android Apps In Easy Steps" by Mike McGrath
  
  It is really much more important for them to learn the conceptual ideas about how programming works, rather than just a coding language. After they learn the basics, it's also important for them to create stuff on their own WITHOUT guided directions, like those in the Codecademy lessons and Scratch activities.
  
  In terms of hardware, for app development you can either go android or apple, which means either getting an android mobile device or apple mobile device. I'd recommend android, that's all I've had experience with and it's pretty great. Windows or Linux are great for coding. Personally, I don't like coding on laptops, but I have before with my school laptop, and it's an HP. So...HP? If you're gonna buy a laptop please make sure it has GOOD memory (8gb or 16 gb should be enough, but the more the better, especially for game development!). Just for the sake of getting the most modern hardware, the central processing unit should be a corei7. Good memory and a good CPU will make the laptop really fast, efficient, and perfect for heavy tasks like compiling/running code or testing a game.
  
  For written programming languages, like Python and C++, you'll need a program to write code on. This type of software is called an IDE, which stands for Integrated Development Environment. Within this software, there are tools used to run code like the "interpreter", "console", "source code editor", and the "debugger."
  
  It's a bit technical, so if you're going to be teaching them then I'd suggest learning the basics about how programming works in general, too.
  
  By the way, coding camps are very expensive but they're useful. Check out CodedByKids, TechGirlz, iD Tech, and maybe FIRST (robotics competition).