On Mac I used switchresx to add a new scaled resolution like this:

2560x1440 (native) * 1.5 = 3840x2160 HiDPI / 2 = 1920x1080 (effective resolution)

Obviously it is not as good a real panel but looked good enough to me.

I did the same thing on Ubuntu using xrandr, it was pretty good when it worked (sometimes it didn't, even using the exact same command)