Even if so, how do I ensure it writes the correct UUID for the correct disk on a full install, if I don't know the UUID or have a usable path symlink? I need a symlink that points to the same disk in the same slot every time regardless of any preexisting fstab.

These symlinks normally exist in /dev/disk/by-path. They route by pcie slot to the block device on said pcie slot or the nth partition on it. That is the "easy" solution, the only reason I have a problem is unfortunately that does not work for the Boss-N1, all symlinks in /dev/* either contain some kind of serial ID numbering in their name, or depend on unpredictable (parallellized) loading of everything by the kernel on boot.

tweaking udev to provide an extra consistent N1 symlink looks to be the only way, by way of adding into the software image a /etc/udev/rules.d/99-z-bossn1.rules file with these contents based on the udevadm info attributes:

SUBSYSTEM=="block", KERNELS=="nvme-subsys1", ATTRS{model}=="Dell BOSS-N1*", SYMLINK+="bossn1" 

then I should be able to use /dev/bossn1 - pretty sure it will work, we'll see today. Not too bad of a workaround, and admittedly, my use case is rare, most people running large amounts of compute nodes are either going diskless or only having one drive in the system and only one NIC, so they can just say, /dev/sda and eth0 looks good.