I should add a README, but…
Where to use them? In your web pages, papers, presentations, …
When to use them?
Packaged: when your software has been packaged for Guix.
Deployed: When you use Guix to deploy your systems, services, software to any number of machines, …
Bit-reproducible: When you use Guix to get reproducible software environments (research, development environments…)
Badges can be linked to Guix for relevant information.