N100 and friends is a good NAS+youtube machine. Some mini PCs allow multiple NVMe drives. For a few more bucks you can get entry-level (but much more powerful) Ryzen CPU in a similar small box
Certainly, if the main use-case is fastest speed in a straight line - get something with a Ryzen like the Acemagic I mentioned at the end with Geekbench scores.
Braindead YouTube-solution would be to buy this device, connect to TV, wireless mouse and install Windows 10/11 LTSC, install firefox + favorite addons. N100 is barely enough for 4k@60, and Ryzen gets a bit more juice to live comfortably