1. Generate STEP files from FreeCAD
2. Generate PDF files from KiCad
3. Unittest (in the future) and generate binary/hex file

As from my point of view all of three sections should be separated in different repos and combined using git submodules, though there are few problems I see, mostly in CAD:

1. CI/CD must know from which input files generate output files - as for now they are kind of mixed in main CAD folder, so my proposition is to create separate folder for:
   1.1 3D_printed parts, as these need to be converted from *.FCStd into *.step
   1.2. 2D drawings parts, like Current Collector Drawing or Gasket Drawings which needs to be translated from *.FCStd into *.pdf
   1.3. Renders which would require rendering whole assemblies - those could be placed in Assembly folder

We would end up with structure of:

.
├── 2D_drawings
├── 3D_print
└── Assembly

2. Electronics is pretty simple, as there will be only KiCAD project, maybe the some kind of electronical/electrical calculations, though I think we are far from it now

3. Similar with Firmware, there would be simply two folders: src and tests, but that is also a next step

I would love to hear other opinions, my idea is to create CI/CD as simple as possible, due to fact that I understand that many ppl who would like to contribute with CAD files might be not familiar with any CI/CD, and for that I came up with that folder idea