DisplaysShouldNotBeTVs Well, I mean linux experience with intel GPU is always not good, and I can not use it for long. It was different with Radeon elitebook, as I have managed to achieve almost zero strain with external monitor on linux X11. Unfortunately I gave away this laptop now to a family member as they needed it. When it comes to windows lenovo is ok, but after longer session I get a bit ungrounded, not sure if this is overwork, shiny screen or something else. When it comes to the purely eye strain - it does not leave residual eye strain after close the lid. Maybe there is slight feeling in the eyes due to shiny screen, but comparing to macbook air m2, it is nothing. So if you want to get new machine, definitely X1 is the one to go. Probably I would suggest carbon X1 as I had one with same WQHD resolution, only matte screen and it was good. It just build quality is a bit of mixed bag with lenovo, my one was crappy, body started to flake off, and battery died, so I had to return it. Regarding FHD, I did not test it, but I know someone in the office who does full time development on ubuntu was happy about it (it was P range, not X1). I specifically asked and there was no problem. And it was slightly higher than FHD, but not (W)QHD.
Update:
T-range to my understanding is the same as X1, but X1 is marketed as premium due to its carbon body. I doubt there are any other major differences. T480 sounds like something from older days, which is positive. T14, T14s which are usually compared with X1 are mixed bag - seen good and bad reviews. Personally I would research P range too. It is more expensive, but this is as I understand lenovo "bread and butter" workstations. Maybe even NASA ISS using those too.