Looks like you have a typo: favorit → favorite.
Also note that the overrides only affect the defaults so if you have already configured the options, you will need to reset them using dconf reset /org/gnome/shell/enabled-extensions so that the system can fall back to the default value.
This is getting documented in nixos/gnome3: add docs by worldofpeace · Pull Request #86288 · NixOS/nixpkgs · GitHub
For better configuration support we have to wait on nixos/dconf: Allow creating custom databases · Issue #54150 · NixOS/nixpkgs · GitHub, or use home-manager, which has dconf.settings option.