GNOME works just fine on hidpi screens. I use it on my (2013) mbp and (2015) chromebook pixel and it looks great.
You do have to use wayland to get scaling across a low dpi external monitor to work, but that has been fairly painless these days (if your GPU is supported by the open source drivers).
You do have to use wayland to get scaling across a low dpi external monitor to work, but that has been fairly painless these days (if your GPU is supported by the open source drivers).