Which one in specific? There are some packages which maintainers did not bother creating xdg desktop specification… you can look into nixpkgs source code to see if they are specified there or not.
I do not know if Debian is able to pick the desktop files though
https://github.com/dessalines/essays/blob/master/why_not_signal.md
I’d also add Jami to the recommended list, even though it is a bit buggy.