A port to other STM devices or even other MCU platforms entirely is definitely possible. My feeling is that the DSP code itself would be reasonably portable to other ARM devices that support the CMSIS DSP library. Chibios, the realtime os Axoloti uses, supports many other devices, so in theory much of the Chibios code could be reused.
I think the basic approach of having the patcher generate firmware source which is then compiled could be improved upon. That approach is very tied to the particular hardware target we have right now. The patcher is very coupled to hardware and the toolchain for that hardware. In the future, I'd like to do something that is more like a proper API, i.e. future hardware targets expose a common API and various clients (one of which would be the visual patcher) could make calls to it. Supercollider's architecure is like this (https://en.wikipedia.org/wiki/SuperCollider#Architecture), there is a clear distinction between the low-level synthesis server and the high-level client language.