[Nix-dev] How do I install firefox nightly or any other program that gets daily updates?

[CodeHero]

So I tried to run firefox nightly by downloading the tar from 
https://nightly.mozilla.org/ and installing a wrapper with the 
directions from 
https://nixos.org/wiki/FAQ#I.27ve_downloaded_a_binary.2C_but_I_can.27t_run_it.2C_what_can_I_do.3F. 
However that did not work. When I try to run the wrapper using 
./result/bin/firefox-nightly it says that the file 
/nix/store/...-firefox-nightly/bin/.firefox-nightly-wrapped does not 
exist although it does exist.

When calling nixos-build firefox-nightly.nix, the build script also 
complains that firefox is not an ELF file, but I don't know if that has 
anything to with it not finding the *-wrapped file.

Now I'm not sure if that's even the best solution or if I can somehow 
make a nix expression that I can add to the global configuration.nix 
that always fetches the current nightly and installs it when i run 
nixos-rebuild.