Hello Richard, thanks for the new information, but really the dbgsym packages were meant. They are available in a separate repository.
Nevertheless, if adding this repository is not possible, then there is another way, but that would download unknown size of files into directory "$HOME/.cache/debuginfod_client", but might be more convenient: export DEBUGINFOD_URLS="https://debuginfod.debian.net" coredumpctl gdb 18825 Kind regards, Bernhard