нуууу, лишь бы железо было хорошим, и все мониторы должны быть 4к, никак иначе
разный dpi не работает
Right, this means that GNOME can only set the same, global scaling factor across all displays.
On Wayland, on the other hand, the display server supports mixed DPI cases, and each window can get a different scaling factor depending on the monitor that is currently displaying it.
Again, there's nothing to fix in GTK: setting the scaling factor is the job of the display server/compositor. GTK only consumes this information.
Additionally, recent versions of GNOME can support Wayland with the nVidia driver—assuming GNOME Shell/Mutter were compiled with EGLStream support. I'm not sure if Debian does that, however, so you may need to make your own packages.