That NUC i5 will do HEVC HDR (aka UHD) -> 1080p without blinking.
It will easily handle 2 of those and likely handle 2 concurrent subtitle burning subtitle streams as well.
As a comparison, I ran my QNAP TVS-1282-i7-7700 to benchmark transcoding performance. Without doing any subtitle burning, all 6 playback devices in the house were running concurrently and there was room for more. The only appreciable load on it was the CPU converting audio.
If you’re going to build it up, 16GB, 512GB NVME SSD. 1TB will last longer (higher TBW value). I use Samsung.
I went with this one but the “Pro” for the extra TBW. (My big fingers don’t work so well anymore so only wanted to do once)
Samsung 970 Pro Series - 1TB PCIe NVMe - M.2 Internal SSD Black/Red (MZ-V7P1T0BW)
