Nice. Ditch WhatsApp. Use an app that has no user identifiers to begin with so no chance of that happening, that is apps like https://simplex.chat/

well i won't be using anything google.

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