Due to a git/gitlab issue they do not contain bundled extensions.

In addition, out of git, the CMake package in it will declare that he is in an "unknown" version and that will be in the version string. Both problems are solved by creating the source package with make dist (or ninja dist) in a build folder for the git repo with the extensions submodule present, using CPack and temporarily replacing unknown with the current git hash.

Unfortunately, there is no way to use the gitlab release list and remove the "default" asset tarballs.

You can find all source tarball at https://inkscape.org/release/inkscape-${version}/source/dl/ and we are working on providing a packager-friendly source download URL page/scheme at inkscape-web#486