Blasphemy!
I'm temporarily back on Windows 
I use Linux Deepin which uses its own DE and I've just bought a 55" 4K TV/monitor. I remember that Wendell said Linux was the best for scaling but turns out my DE's HiDPI support is in the roadmap but not here yet.
I don't want to install something Elementary OS or use Windows. What are my options?
Ubuntu Gnome has pretty good scaling, I believe Wendel uses Gnome for his DE so that would probably be what he is talking about.
Gnome has integer scaling, KDE also has scaling
Thanks for the replies. So there is no way I can make Deepin scale? No way I roughly hack it until the official release?
install gnome/kde . you can switch between the 3 at the gui login screen.
I'm using Arch with Gnome 3 with 2 x 4K 28" monitors and it seems to scale well out of the box. All I changed was increased the font scaling factor to 1.50.
I had heaps of issues with Ubuntu Kubuntu and Fedora with scaling.
Mainly just didn't like KDE and Ubuntu was moving away from Unity (which did scale very well) so I wanted a distro that I could use longterm.
no, deepin is very behind in terms of development.