Can confirm, got Darktable working with Canon R6 Mk III CR3 raw files on Ubuntu 24.04.
Did the git clone of DT:
git clone --recurse-submodules --depth 1 GitHub - darktable-org/darktable: darktable is an open source photography workflow application and raw developer · GitHub
Downloaded the zip from here:
Unzipped, moved LibRaw to /darktable/src/external then from darktable source ran this:
./build.sh --prefix /opt/darktable --build-type Release --install --sudo
Many errors, apt install <many_pkgs>, build.sh finally compiled and built DT wihtout errors and installed in /opt/darktable.
cd /opt/darktable/bin and exec darktable. Comes up clean, can import CR3 files and edit them successfully.
Thanks for all help especially @MStraeten