There is a publicly available Devkit[1] for the processor used by M-VAVE in all of their products:

https://doc.zh-jieli.com/AC79/zh-cn/release_v1.0.3/board_des...

.. and .. as all of their products are extremely good value for money .. I dare say some budding hacker saw an opportunity and went with it:

https://github.com/aroum/fm1-custom-fw

This has opened the flood gates for great new stuff to be written for it, and oh what a ride it has been these past few weeks! Simply the hottest toy in music-tech, bar none!