Pen support on linux is amazing. On the T935 it worked without any setup and was much better than on windows in terms of input lag and turning the touchscreen off/on properly.

I used Xournal++ and while the UI is a bit small on a 13" 1080p screen, it worked perfectly.

Now I remember another thing you should probably look out for: Don't get anything with a higher resolution than 1080p. Fractional scaling on linux is basically not a thing, so the resolution determines the size of any UI.