I understand that environments are for developing projects installing
dependencies in a separate space in order not to clutter the main
installation.

Say I want to work on a ruby based project. This is an hypothesis, actually
I have never seen a single line of ruby code in my life

Now, this project has a gem file downloading tons of components that the
project depends on.

Is it possible to type

guix environment ruby

then inside such an environment run bundler (or how it is called) and have
it do its thing ?

It will download to the local project folder not trying to affect anything
outside the project, right ?