Using Nix-shell to create reproducible embedded development environments

I recently started using nix but something I haven’t found yet is an ability to dump the current nix shell environment to a shell.nix file

Eg, I invoke `nix-shell -p somepkg anotherapp andathird`, per the manual, decide it’s a satisfactory setup, and so I want to save that to a shell.nix to keep using - does this functionality exist through some command or tertiary app?