The micro:bit uses micropython - 16Kram and 256K Flash memory. I'd still use C++ (or probably machine code for larger production runs) in anger but you can teach lot in micropython and you have to learn a lot to use C++ properly - but then you have to learn the same stuff to use programming properly.
Have you tried ROOT - https://root.cern.ch/ - it a sort of interpreted C++.
If I wasn't trying to teach people coding I'd re-write Zim in ROOT and use that for documenting the C++ code that falls out of it at the moment. For now I am happy to teach Python and hope they learn enough to switch to C++ rather than using the python interface to it that is almost ubiquitous these days!
The micro:bit uses micropython - 16Kram and 256K Flash memory. I'd still use C++ (or probably machine code for larger production runs) in anger but you can teach lot in micropython and you have to learn a lot to use C++ properly - but then you have to learn the same stuff to use programming properly.