Is your feature request related to a problem? Please describe.
I would like to more easily serve a different store than the default /nix/store. The alternative NIX_REMOTE=local?/path/to/store nix-daemon --stdio doesn't create the necessary directories or work well in the docker image. I would prefer nix daemon --stdio --store /path/to/store

Describe the solution you'd like
nix daemon should accept --stdio.