How can I configure a custom TeXLive Docker image on Debian to properly load fonts?

I used this one

DOCKERFILECopied
    FROM registry.gitlab.com/islandoftex/images/texlive:base

# whether to install documentation and/or source files
# this has to be yes or no
ARG DOCFILES=no
ARG SRCFILES=no
ARG SCHEME=full

# the mirror from which we will download TeX Live
ARG TLMIRRORURL

# whether to create font and ConTeXt caches
ARG GENERATE_CACHES=yes

# Make sure apt-get never asks a question (https://manpages.debian.org/testing/debconf-doc/debconf.7.fr.html#noninteractive)
ENV DEBIAN_FRONTEND=noninteractive

WORKDIR /tmp

# download and install equivs file for dummy package
RUN curl https://tug.org/texlive/files/debian-equivs-2022-ex.txt --output texlive-local && \
  sed -i "s/2022/9999/" texlive-local && \
  # freeglut3 does not ship with debian testing, so we remove it because there
  # is no GUI need in the container anyway (see #28)
  sed -i "/Depends: freeglut3/d" texlive-local && \
  apt-get update && \
  # Mark all texlive packages as installed. This enables installing
  # latex-related packges in child images.
  # Inspired by https://tex.stackexchange.com/a/95373/9075.
  apt-get install -qy --no-install-recommends equivs \
  # at this point also install gpg and gpg-agent to allow tlmgr's
  # key subcommand to work correctly (see #21)
  gpg gpg-agent \
  # we install using rsync so we need to have it installed
  rsync \
  # 2024-11-05 debian:testing-slim does not offer libcurl, needed by asy (#48)
  libcurl4t64 && \
  # we need to change into tl-equis to get it working
  equivs-build texlive-local && \
  dpkg -i texlive-local_9999.99999999-1_all.deb && \
  apt-get install -qyf --no-install-recommends && \
  # reverse the cd command from above and cleanup
  rm -rf ./*texlive* && \
  # save some space
  apt-get remove -y --purge equivs && \
  apt-get autoremove -qy --purge && \
  rm -rf /var/lib/apt/lists/* && \
  apt-get clean && \
  rm -rf /var/cache/apt/

RUN echo "Fetching installation from mirror $TLMIRRORURL" && \
  rsync -a --stats "$TLMIRRORURL" texlive && \
  cd texlive && \
  # create installation profile for full scheme installation with
  # the selected options
  echo "Building with documentation: $DOCFILES" && \
  echo "Building with sources: $SRCFILES" && \
  echo "Building with scheme: $SCHEME" && \
  # choose complete installation
  echo "selected_scheme scheme-$SCHEME" > install.profile && \
  # … but disable documentation and source files when asked to stay slim
  if [ "$DOCFILES" = "no" ]; then echo "tlpdbopt_install_docfiles 0" >> install.profile && \
    echo "BUILD: Disabling documentation files"; fi && \
  if [ "$SRCFILES" = "no" ]; then echo "tlpdbopt_install_srcfiles 0" >> install.profile && \
    echo "BUILD: Disabling source files"; fi && \
  echo "tlpdbopt_autobackup 0" >> install.profile && \
  # furthermore we want our symlinks in the system binary folder to avoid
  # fiddling around with the PATH
  echo "tlpdbopt_sys_bin /usr/bin" >> install.profile && \
  # actually install TeX Live
  ./install-tl -profile install.profile && \
  cd .. && \
  rm -rf texlive

WORKDIR /workdir
RUN echo "Set PATH to $PATH" && \
  $(find /usr/local/texlive -name tlmgr) path add && \
  # Temporary fix for ConTeXt (#30)
  (sed -i '/package.loaded["data-ini"]/a if os.selfpath then environment.ownbin=lfs.symlinktarget(os.selfpath..io.fileseparator..os.selfname);environment.ownpath=environment.ownbin:match("^.*"..io.fileseparator) else environment.ownpath=kpse.new("luatex"):var_value("SELFAUTOLOC");environment.ownbin=environment.ownpath..io.fileseparator..(arg[-2] or arg[-1] or arg[0] or "luatex"):match("[^"..io.fileseparator.."]*$") end' /usr/bin/mtxrun.lua || true) && \
  # pregenerate caches as per #3; overhead is < 5 MB which does not really
  # matter for images in the sizes of GBs; some TL schemes might not have
  # all the tools, therefore failure is allowed
  if [ "$GENERATE_CACHES" = "yes" ]; then \
    echo "Generating caches and ConTeXt files" && \
    (luaotfload-tool -u || true) && \
    # also generate fontconfig cache as per #18 which is approx. 20 MB but
    # benefits XeLaTeX user to load fonts from the TL tree by font name
    (cp "$(find /usr/local/texlive -name texlive-fontconfig.conf)" /etc/fonts/conf.d/09-texlive-fonts.conf || true) && \
    fc-cache -fsv && \
    if [ -f "/usr/bin/context" ]; then \
      mtxrun --generate && \
      texlua /usr/bin/mtxrun.lua --luatex --generate && \
      context --make && \
      context --luatex --make; \
    fi \
  else \
    echo "Not generating caches or ConTeXt files"; \
  fi

RUN \
  # test the installation; we only test the full installation because
  # in that, all tools are present and have to work
  if [ "$SCHEME" = "full" ]; then \
    latex --version && printf '\n' && \
    biber --version && printf '\n' && \
    xindy --version && printf '\n' && \
    arara --version && printf '\n' && \
    context --version && printf '\n' && \
    context --luatex --version && printf '\n' && \
    asy --version && printf '\n' && \
    if [ "$DOCFILES" = "yes" ]; then texdoc -l geometry; fi && \
    if [ "$SRCFILES" = "yes" ]; then kpsewhich amsmath.dtx; fi; \
  fi && \
  python --version && printf '\n' && \
  pygmentize -V && printf '\n'

Works on Ubuntu 24.04.