Do you have an IPS display for your X220? It doesn't increase the resolution, but it does make it much better. (The X220 is pretty easy to swap the screen on too.)
No I don't, but I am looking to swap the TN display with a FHD IPS screen, as mentioned in [0], but sadly there are very few aftermarket kits around these days last I've checked.
I have a couple of the FHD mods from here ( https://forum.thinkpads.com/viewtopic.php?t=122640 ), but they took quite a while to get to me, and by then my enthusiasm for experimental soldering had waned, but sometime I will try.
But even just swapping in an 1366x768 IPS panel for the TN panel of the same resolution makes a great difference. And those you can find fairly cheaply.
[0] https://hackaday.com/2016/08/26/making-a-thinkpad-great-agai...