From some previous threads about the display, I think replacing the display would be quite difficult, because it is glued to the laptop chassis. Perhaps Purism has the tools and skills to undo that glue and redo it, but I typically think of glue as kinda permanent, just 'cause undoing it usually really sucks and leaves residue, etc.
As @ramnasko said, the video card is just the Intel integrated graphics card that comes with the CPU. I know they didn’t have to change the motherboard between v3 and v4, so the newer CPU model they’re using would fit, but I’ve never tried swapping a laptop CPU before, so I don’t know what kind of soldering skills and equipment might be needed.