All you could do is transplant a working 5k display from LG or other maker into the case. You can’t use a iMac 5k display as you will still need the driver logic and the interface logic.
Not sure if it’s worth the effort. Between the trying to figure out how to fit the display and needing to design and make the mounting hardware (3D printer?)
I’m hoping Apple rolls out a lower cost display for the rest of us! The XDR is a fantastic display for video work when you need the color reference it offers but its just too expensive for most everyone else!