Most or all of the motherboard ports are dead once the OS loads - it's a highly narrow write of OS. Even USB keyboards won't work, only PS/2 lol. (Keep one around for bios issues!)
I haven't done it, but according to my memory it's VGA for video, Serial Data for touchscreen data, and power. Hardware switching to another screen should be easy since that is a standard touchscreen data method, software is a different story. That OS is pretty strict in it's operating parameters - I'm assuming it's linux based and does not support anything extra of OEM configuration. That means a new resolution for your new screen won't work. You should be able to upsize screens at the same compatible resolution/screen size, or possibly upscale but only at exact ratios. If you check your BIOS you'll find the resolution should be hard-set, then just choose a screen upsize from there.
Sure anything is possible, but not everything is worth it lol. Those little printers are a nightmare, hence why they are littered across the world with low mileage for next-to-nothing. If it's worth it to you or a project, those are the details that should work. But equipment productivity in mind only, I would deal with it for a year or two if you can make a better printer your next major purchase. Of course I don't know what your situation is! The spice of life is that you can strategize and do things however you like
Now if you DO get it working, post it back here so we see the outcome!