I have available a Dell XPS 13 notebook that was scrapped some time ago because none of the USB ports works anymore. (This eliminates charging the battery or running on the power supply. Probably just some tiny crack in the junction between the main board and the port device, or similar, but there is nobody to be found to repair it.)
I now came across an offer for a very cheap XPS 13 notebook of similar format with a damaged screen, and a thought of possibly combining the working parts of the two pc’s naturally comes to mind.
However, the damaged screen has a larger resolution than the working one. Is this just a matter of drivers that I can expect to be solved when installing linux on a fused computer, or must I expect to encounter some intractable hardware/firmware issue.
Not necessarily. And since the mainboard is available as a single unit, repair would pretty much entail replacement. Sometimes these are available as used items for units cannibalized for other reasons (eg on ebay), so this would be the first thing I would try.
But note that it would make sense to diagnose the problem first; you could end up buying parts you do not need.
If you know the precise laptop models, you can look up the connector types and the exact screen dimensions (they could be different by 0.5mm and not fit), this is what I would check first. Similarly, if you are trying to transplant the mainboards, they may not fit either.
FWIW, I don’t repair my own laptops but take them to a professional. I have proposed to him similar schemes before (use the screen from an Asus laptop that had water damage in another that had screen damage), but I was told that he won’t even look into it, as there is a 99% chance that I would just be paying for hours of labor with no outcome, and even if the parts fit he cannot give me any kind of warranty, so many things need to match and a few mm differences means that he cannot reassemble the laptop in a reliable way.