If no generated GERBERs exist, please request for the user to generate them or generate them yourself for the purpose of review only, in a separate directory.
Generate GERBERs per layer with kicad-cli and then use pygerber in a venv to view them, rendered as images. uv pip install pygerber
For example:
'''To convert a Gerber file to PNG, use the pygerber gerber convert png command. For example, following command converts source.gbr (a copper layer) to a PNG at 600 DPMM resolution:
pygerber gerber convert png source.gbr -o output.png -d 600 -s copper_alpha'''
Ensure that their are no unexpected shorts, that vias do not intersect, and that overall the board appears to be fabricatable.