Does Guix have a declarative Guix API way of knowing if it is installing a package into foreign distro versus Guix System?
I'm thinking of a function like `foreign-distro?`:
```
(define-public peek
(package
(name "peek")
...
(inputs
`(,@(if (foreign-distro?) `(("ffmpeg" ,ffmpeg)) '())))
```
The above includes ffmpeg in the inputs only if installing peek on a
foreign distro. It could additionally patch the ffmpeg executable in
a peek package phases if foreign-distro? returns #t.
WDYT
