From what I know Plex is the simplest solution between my qnap TS-230 and LG CX Oled. Kodi doesn't run on LG OS. This way I don't need any additional device. Without transcoding the TS-230 allows smooth 4k HDR playback even with bitrates up to around 100Mbit/s above that it gets stuttery. But I must say I can't really tell the difference above ~60Mbit/s.
But I love being corrected.