Install a snippet in bash_completion.d to load python3-argcomplete, as a conffile

debian/global-python-argcomplete

+# Enable python-argcomplete global completions
+# This checks for a PYTHON_ARGCOMPLETE_OK in the first 1024 bytes of any
+# executable, and if found will attempt to use argcomplete completions.
+
+if [[ -e /usr/lib/python3/dist-packages/argcomplete/bash_completion.d/_python-argcomplete ]]; then
+	. /usr/lib/python3/dist-packages/argcomplete/bash_completion.d/_python-argcomplete
+fi

debian/python3-argcomplete.dirs

-/usr/share/bash-completion/completions
 /usr/share/zsh/vendor-completions

debian/python3-argcomplete.install

+debian/global-python-argcomplete /etc/bash_completion.d/

debian/python3-argcomplete.links

-/usr/lib/python3/dist-packages/argcomplete/bash_completion.d/_python-argcomplete /etc/bash_completion.d/_python-argcomplete
 /usr/lib/python3/dist-packages/argcomplete/bash_completion.d/_python-argcomplete /usr/share/zsh/vendor-completions/_python-argcomplete