Kenny Ballou <kballou@devnulllabs.io> writes:

> I would like to be able to specify a project's dependencies in a
> manifest file, add any environment variables as necessary, and have
> Emacs be aware of those variables when entering that environment.

It may not be what you're looking for, but projects like Haunt [1] put a
guix.scm file in the root directory of their project.  The file contains
a package as its top-level form (I think that's the right terminology),
and you can get the dependencies via "guix environment -l guix.scm".

Hope that helps!

Footnotes: 
[1]  http://haunt.dthompson.us

-- 
Chris