I primarily use PDSOE for dev work, along with some VS Code and UltraEdit. I have a Dell laptop with 4K display, and a few other external displays, full HD and below. In Windows I set the main (laptop) display at 200% scaling and the others at 100%. I prefer 200% over the "recommended" 300% as it's a compromise between reasonable readability and increased screen real estate that works for me. I do development work on the external 24" displays as they are much larger than the 13.3" laptop display.
Pretty much every application I use scales properly, except for PDSOE (Eclipse), but there is a workaround for that. Instead of launching PDSOE with PSC's batch file, I just run Eclipse directly, and use Windows compatibility settings to override the default scaling for it and use "System (Enhanced)". That makes the text and UI elements size correctly on all displays.
Everything else from Progress (Procedure Editor, Data Dictionary, proenv, etc.) works fine on all of my displays.
I definitely don't regret opting for the 4K display. It's beautiful and works well. If you're doing day-to-day development work and you have the luxury of working in the same place every day (i.e. not hoteling) then I strongly recommend buying a nice large external display, or two. If that device has an Intel 11th-gen or better CPU and a Thunderbolt 4 port then it can drive two external 4K displays at 60 Hz, plus the internal display. I don't have that setup yet but that's my plan for later this year.
I have run my current setup in both Windows 10 and Windows 11. From this perspective, I found no difference between the two.