Back to your problem. Doesent windows 10 native scaling cure that problem?
Or even choose say 1600 x 900 resolution for the moment?
As a microbial genetecist colleague of mine was won't to say "It's not that simple". Yes, one can change the Win10 scaling factor and/or screen resolution and probably get the old gaze tracker software to fill the screen and calibrate, but the tracker is used as input to other programs that actually do scale properly for the 3000 x 2000 screen. Futzing with Win10 settings to make the tracker software work destroys the foreground windows with which it interacts.
The version of WordPerfect that I'm still using, WP 18, illustrates what happens when software hasn't been updated for high res screens. The main document window, and most WP feature and tool bars do scale properly, but when they updated WP to 18 someone forgot about some of the subsidiary dialogs. For example, the macro toolbar and the macro command inserter and its context help dialog do not scale, so they're really tiny and rather a strain for my old eyes. This has supposedly been fixed in version 20, but with 21 having recently been released I am waiting for others to expose some of its bugs before I upgrade. Corel asked me to be a beta tester for WP21 (which would have given me a free copy, as well as a chance to bitch once again about long-standing bugs that haven't gotten fixed), but it was a case of the left hand not knowing what the right hand was doing because they actually released it for sale less than a week after asking me.
Newer versions of the tracker software have supposedly been re-written for Windows 10 and even include a settable scaling factor (though that is probably only relevant for older Win10 before the auto-scaling was working decently). At least I hope it will work properly without f--king up the foreground windows.
What's the angle of view on your new portable? HP has a 1000 nit screen available for the X360-14 convertible, but they achieved that by going to an extremely narrow viewing angle - then advertise this as a privacy "feature" for use in office environments. The 400 nit OLED is too bright for normal room light and good outdoors if not in strong, direct sunlight, but I did have to add a control for screen brightness to Rachi's program because the keyboard (with its brightness F keys) is deactivated when folded back to mount on Rachi's chair. She can now, with a few switch clicks, turn brightness up and down in 10% steps. That function overlays more or less transparent black over the screen, which with the OLED doesn't impose any power use penalty. If it were a backlit screen painting black over the screen image would be a real power waster and would also raise temps quite a bit. To actually mimic the real brightness control would require having the API for HP's screen driver (I think it's actually an Intel driver), but they'll won't supply that to mere mortals. HP actually promised twice to bring the problems I was having to the attention of the appropriate "team" and promised a rapid response - a response that never, ever arrived so I was forced to roll my own.
The power switch is also a key on the keyboard, so there was no way to turn the folded computer off either, or to turn it back on without taking it off the chair and unfolding it. I cured that by mounting a flip up magnet to fool the "laptop keyboard closed" switch and having that set it to sleep. Magnet UP = sleep, magnet DOWN = awake.