the tl;dr of that spreadsheet is that some QNAP NAS devices (higher priced ones) do OK... Synology do bad, most will struggle to do anything at a high resolution and your Plex server will likely refuse to play (or crash - which is what happened with mine).
Shield gets your further... but only for some codecs.
Hence... once I'd acquired enough media to encounter these restrictions, I went for a fanless PC to run Plex.
Oh...
And Plex hardware transcoding information:
There's a big datasheet on Plex and NAS support for transcoding features https://docs.google.com/spreadsheets/d/1MfYoJkiwSqCXg8cm5-Ac4oOLPRtCkgUxU0jdj3tmMPc/edit#gid=1274624273
the tl;dr of that spreadsheet is that some QNAP NAS devices (higher priced ones) do OK... Synology do bad, most will struggle to do anything at a high resolution and your Plex server will likely refuse to play (or crash - which is what happened with mine).
Shield gets your further... but only for some codecs.
Hence... once I'd acquired enough media to encounter these restrictions, I went for a fanless PC to run Plex.