This morning I got a Pixl.js Espruino board for Father's Day. My son is not even two years old - how did he know that is exactly what I wanted?
It works over Web Bluetooth, so you connect to it from the Espruino Web IDE. The only thing I had to do to get it working on Ubuntu 18.04 was to enable the "Experimental Web Platform Features" under
chrome:flags on Chrome and then go to espruino.com/ide.
I then tried to get it working on my iPad. Unfortunately Web Bluetooth is not yet supported on Safari, but there is a WebBLE browser you can download from the app store (for £2) that does. It's a very basic browser, but all you really need it for is to run the Espruino Web IDE. That I can program a little micrcontroller over Bluetooth from my iPad blows my mind!