Hi, and welcome! I have browsed your github code on several occasions while I was developing a module (Vocode-O-Matic) for VCV-Rack.
We seem to be on somewhat similar paths (although I have no ambitions on selling any of my software/designs (yet)). I also want to make hardware and started out with software. The reason I made the VCV-module was that I wanted to redesign my file based vocoder to become a real time version in hardware (actually on an FPGA) and VCV-Rack made it possible to test the real time version of its core software as an intermediate stage. I’ve recently implemented it on a Daisy Seed (not an FPGA) and posted about it in this thread. I’m currently working on a real time spectral display to add to it.
What I found difficult about making a module for VCV-Rack is the lack of documentation on the basic structure of a module and how it interacts with the engine etc. Apart from a link to some example code, there is not much of a tutorial to get you going. Most problems I encountered had nothing to do with the DSP-side of things (that worked from the start) but were related to the C++ api and basic structure of a module.