I've done some testing and a bit of research.
Basically the Poser UI scaling setting appears to have no bearing on the scaling of Python scripts.
Whatever the UI scaling setting of Poser (tested from 1.0 up to 2.0) the scripts look fine as long as the Windows scaling is set at 100%. Anything above this and the UIs start to deteriorate becoming all but unusable by 200% (which is the point at which I can read the screen).
The upshot is that basically Poser doesn't seem to add, or take away anything from Python as such and therefore any method of making a script "DPI Aware" in Python should work equally well in Poser. I know, from bitter experience how difficult it is to ensure that UI's scale properly from using Windows Forms back in the day (I use WPF now when I get the chance to do any coding). It can be done, however - EZSkin3 by Snarlygribbly scales perfectly at all DPI settings and that is free software. He has even released the source code.
If not for Octane 3 then is it at least on the cards for Octane 4 to be able to scale the UI so that it doesn't look like a dogs dinner using anything above a "normal" screen?
Back in 2014 I was considered an "early adopter" of 4k and had to jump through hoops to get anything at all to look good. Now, 4 years later, this kind of display is becoming mainstream. Some software publishers have embraced it; Smith Micro have done a great job with Poser 11, they have a scaling option in the program which smoothly allows me scale the UI to any level. It seems odd that they should then hamstring any add-ons.
Some script authors have managed to code their UI to work perfectly so it can be done and should work, especially for expensive software (Octane for Poser costs twice as much as Poser!)