That requires your network attached storage (NFS/iSCSI or something else) to be HA ;-) I started booting from USB SSD a couple of months ago since I got my Pi

That requires your network attached storage (NFS/iSCSI or something else) to be HA ;-) I started booting from USB SSD a couple of months ago since I got my Pi 8GB, intended to use it as my low power consumption workstation replacing the Optiplex SFF Running Manjaro + KDE Plasma. Turn out to be, Manjaro ARM + KDE Plasma on Pi 4 runs pretty well (even all KWin eye candies work as well as the Intel HD integrated GPU on the x86_64 variant). However, USB 3.0 to SATA III SSD is clearly a bottleneck still. I am yet to check if NFS over 1Gbps ethernet can be faster (anyway, my btrfs backed consumer grade NFS may not be production grade to support 10+ devices).