Well, if you want to use it to watch Netflix 4K UHD streaming videos, the minimum NVidia card that you need, is a GTX 1050 3GB. Which I have in my FS/FT, it just happens. PM me if interested.
Other than that, any Polaris or Maxwell V2 or Pascal, or Vega, or Turing, card will do HDMI 2.0 output.
An NVidia GT 630 / 730 (Kepler) card, will also do 4K@60 over HDMI 1.4 at reduced color depth, due to a nice little HDMI "hack" feature, that overdrives the HDMI port slightly on those cards. (I've tested it with my 40" 4K UHD screens.)
As far as APUs / CPU iGPUs go, for AMD, Raven Ridge (Ryzen 2200G / 2400G for AM4 socket) will do HDMI 2.0 output. On Intel, things aren't so rosy, and current Skylake, Kaby Lake, and Coffee Lake HDMI outputs are still stuck at HDMI 1.4, and will NOT (thus far) allow you to overdrive the HDMI 1.4 port or reduce the color depth to do 4K@60 output. They will only do 4K@30, over HDMI. If the board has a DisplayPort, you can do 4K@60 over that, and need an active adaptor (like a Club3D) to convert the signal to HDMI 2.0. (I've done that too.)