A great new target arrived onto the scene: KittenBot Bridge
just received this last Friday and so far haven’t had a lot of time to ‘play’ with this, but I do notice that some essentials are still missing. For instance, since there the pin mapping is not known, I haven’t been able to attach a simple TFT yet to the board and try running it with Arcade (target SAM D51). All so far I have been able to do was make the LED blink and use Maker.
It does have a test target at http://maker.kittenbot.cn/ but it does not allow the use of adding extensions. They all fail … Hope more information will arrive, but so far my issues on GitHub and by email have done unanswered.
Note: you might notice there the SD-Wireless inserted to the right. This device allows to communicate with the Micro:bit, but the library https://github.com/KittenBot/pxt-sdwireless did not work for me with this board, and impossible to add to their Maker target. It does work with the Meowbit.