The README.md currently fails to mention any software dependencies (except Qt in general).
These packages from the official Archlinux repositories were required for me to build and start Graphia: qt5-base qt5-3d qt5-declarative qt5-quick3d qt5-quickcontrols qt5-quickcontrols2 qt5-graphicaleffects qt5-svg (I'm not sure that each one was necessary, though. And I may have missed some dependencies.)
EDIT: another thing that should be documented are the dependencies on the GPU stack. E.g., if Graphia uses Vulkan (I don't know if it does), there are probably additional packages that I need to install.