For everyone who came here with the same questions about green screen on remote transcoding and similar QNAP HW, I’ve been reading about the Xeon E3-1246v3 and his integrated Intel HD Graphics P4600 GPU. Seems like it has an hybrid (CPU/GPU) decoding implemented and can decode hevc 265 8bit but not 10bit:
my previous plex servers ran Xeon E3-1225v3 and E3-1275v3 with the same iGPU. I can confirm PLEX would indeed hw transcode some HEVC. Not consistently, even on the same file … but some support was implemented and functioning.