The topic I turned a boat anchor (QNAP TS-451) into a TrueNas server (now bare-metal install) refers to the install of TrueNAS on much older QNAP hardware. Not sure, what of that applies to the TS-464eU. There are references to (very small) QNAP DOMs in that thread, but I don’t know, whether the TS-464eU has one of those, or even whether it is 16 GB or larger.