Missing dependency building the pc-kernel snap

I need to add a kernel module to the kernel snap of an Ubuntu core image. I first tried to do this using insmod, but this failed because the filesystem is read-only. Now, I am trying to add the module to the kernel snap itself. I downloaded the pc-kernel snap (22/stable) and unsquashfs’ed it. Before trying to add my own module, I first wanted to see if I could successfully build it. For reference, here is the snapcraft.yaml file associated with this snap:

name: pc-kernel
adopt-info: kernel
grade: stable
summary: generic linux kernel
description: The generic Ubuntu kernel package as a snap
type: kernel
confinement: strict
build-base: core22
# In addition to these repositories, the /+snap/ page on launchpad may
# also build with ESM repositories enabled, or built in a particular
# PPA, which will also be used.
  - type: apt
    ppa: canonical-kernel-team/uc20-release

    source: https://git.launchpad.net/~canonical-kernel-snaps/+git/kernel-snaps-uc22
    source-type: git
    source-branch: main
    plugin: nil
    # Set this snap version to the meta version of the package used to
    # provide kernel.efi / vmlinuz
    override-pull: |
      snapcraftctl pull
      snapcraftctl set-version "$(apt show linux-image-uc22-generic 2>/dev/null | sed -n 's/^Version: //p' | head -n1)"
      - kmod
      - linux-image-uc22-generic
      - on amd64:
        - firmware-sof-signed
      boot: ./
      lib/firmware: firmware
      lib/modules: modules
      usr/share/doc: doc
    override-build: |
      if [ -e "$SNAPCRAFT_PART_INSTALL"/usr/share/doc/linux-image-uc22-generic/kernelefi.stamp ]; then
        rm -vf "$SNAPCRAFT_PART_INSTALL"/boot/vmlinuz-*
        mv "$SNAPCRAFT_PART_INSTALL"/boot/vmlinuz-* "$SNAPCRAFT_PART_INSTALL"/boot/vmlinuz
      if [ -d "$SNAPCRAFT_PART_INSTALL"/usr/share/doc/linux-signatures-nvidia-*-generic ]; then
        cd $(dirname "$SNAPCRAFT_PART_INSTALL"/lib/modules/*/kernel/nvidia-*/bits/SHA256SUMS)
        sh BUILD
        # Remove nouveau
        rm -rf "$SNAPCRAFT_PART_INSTALL"/lib/modules/*/kernel/drivers/gpu/drm/nouveau
        # Update depmod
        depmod -b "$SNAPCRAFT_PART_INSTALL" $(basename "$SNAPCRAFT_PART_INSTALL"/lib/modules/*)
        # Trim firmware
        "$SNAPCRAFT_PART_SRC"/trim-firmware "$SNAPCRAFT_PART_INSTALL"/lib
        # Clean nvidia modules
        sh CLEAN
        # Fake the nvidia.ko modules pointing at an nvidia assemble location
        cd ../
        for module in nvidia-drm.ko nvidia-modeset.ko nvidia-peermem.ko nvidia-uvm.ko nvidia.ko
          ln -s /var/snap/nvidia-assemble/common/nvidia-driver/$module $module
        # Update depmod
        depmod -b "$SNAPCRAFT_PART_INSTALL" $(basename "$SNAPCRAFT_PART_INSTALL"/lib/modules/*)
        # Trim firmware
        "$SNAPCRAFT_PART_SRC"/trim-firmware "$SNAPCRAFT_PART_INSTALL"/lib
      snapcraftctl build
    # Exclude transitive dependencies of userspace stage-packages that
    # do not make sense in the kernel snap. E.g. iw tool is shipped in
    # base snap, but kernel needs to ship regulatory-db datafiles
    # alone.
      - -etc
      - -lib
      - -usr
      - -sbin
      - -bin
      - -var
      - -lib64
      - -doc/linux-base
      - -doc/binutils*
      - -doc/debconf
      - -doc/dpkg
      - -doc/gcc-*
      - -doc/kmod*
      - -doc/lib*
      - -doc/lsb-base
      - -doc/perl*
      - -doc/tar
      - -doc/zlib1g
    override-stage: |
      snapcraftctl stage
      # Check that only one nvidia series got shipped
      if [ "$SNAPCRAFT_TARGET_ARCH" != "armhf" ]; then
        [ $(ls "$SNAPCRAFT_STAGE"/modules/*/kernel/nvidia-*/bits/SHA256SUMS | wc -l) -eq 1 ]

Building the kernel snap with snapcraft fails because a dependency linux-objects-nvidia-525-server-5.15.0-86-generic for the package: linux-image-uc22-generic can not be resolved. After some digging, it appears as though linux-image-uc22-generic requires linux-objects-nvidia-525-server-5.15.0-86-generic=5.15.0-88.98, but the only available version is linux-objects-nvidia-525-server-5.15.0-86-generic=5.15.0-88.98+1.

How can I get around this issue to build the kernel snap? I’m assuming it’s possible because it had to have been built at some point - unless I am missing something about how unsquashfs works on snaps.