Unfortunately there is a lack of easy to use tooling... Mu for the microbit is nice, but other platforms don't have an easy to use editor and file uploader
Do you mean other hardware platforms upon which MicroPython runs, or other software platforms that target the micro:bit? If the former, work is in progress on that front (I am the maintainer of Mu).
Hi! I've been working on adapting mu for other platforms (askvictor/eduvik). My main concern is other hardware platforms (microbit support is great) - there's nothing which 'just works' for esp8266 and other serial-based devices, so any students I point in that direction have to get through a heap of unnecessary technical hurdles to get up and running.