Any there any open CAD file formats that lay a foundation for describing this kind of 3D data without classic triangles?
CAD uses geometry primitives with parameters and exact sizing (e.g. you draw a rectangle of this size, and cut a whole into it this and this offset from one of the corners, and you expand this shape to 3D). As mentioned this can be approximated via geometry nodes, but they are very different in "ideology".
Blender has and extension for IFC called Bonsai. https://extensions.blender.org/add-ons/bonsai/