hello an_actual_toaster,
suggest you check Topic 1032951 , and also Using the initial RAM disk (initrd) for reference.
there’s an issue that /boot/initrd.img appears to be broken after JP-4.4, the initrd.img is too big for usage,
please refer to these discussion thread, Topic 78540, and Topic 191060, for simple fixes to switch from the default MODULES=most to MODULES=dep.
there’s another discussion thread, linuxquestions.org talking about how to setup a readonly rootfs without an initramfs.
thanks