Thanks for the awesome feedback!
It’d be awesome if you can pull request or just suggest your changes on the package repository here: https://github.com/beganovich/snappdf
SNAPPDF_EXECUTABLE_PATH=/usr/bin/chromium
SNAPPDF_SKIP_DOWNLOAD=true
Variables should be exported globally (just like CHROMIUM_FLAGS) for now, but I plan to add them into Invoice Ninja.