usearegex

You have to specifically grant permission to websites to let them send you notifications, Safari will ask you the first time you visit the site similar to how sites can request your current location. You can change these settings later through the Safari preferences.

"Can I download the OS to try it out? You will be able to download it (including the source code, if you're into that)"

So it will be open source...

One device with such a low barrier to getting started programming that kids still have access to is TI graphing calculators - I got into programming through my TI-84 back in middle school, writing quadratic equation solvers and the like , and eventually playing with graphics and simple games. I certainly wouldn't recommend that anyone specifically choose the calculator as a starting platform, but it's a great way to accidentally discover programming. And it was a great way to kill time at school for several years...