I've added a news-file entry to my channel:

--8<---------------cut here---------------start------------->8---
(channel
 (version 0)
 (news-file "news.scm"))
--8<---------------cut here---------------end--------------->8---

which contains

--8<---------------cut here---------------start------------->8---
(channel-news
 (version 0)
 (entry (commit "25387230a7f99c2b0886488ed061747c9e00434a")
        (title (en "Hello"))
        (body (en "World!"))))
--8<---------------cut here---------------end--------------->8---

Reading the news file from the REPL works.

--8<---------------cut here---------------start------------->8---
(with-input-from-file "/home/ambrevar/projects/foo/news.scm"
                          (lambda ()
                            (read-channel-news (current-input-port))))
--8<---------------cut here---------------end--------------->8---

However, guix pull chokes on it:

--8<---------------cut here---------------start------------->8---
(repl-version 0 0)
(exception unbound-variable (value #f) (value "Unbound variable: ~S") (value (channel-news)) (value #f))
--8<---------------cut here---------------end--------------->8---

I first encountered this issue in Feb 2020, but this issue might have
been around since channel news were introduced.

-- 
Pierre Neidhardt
https://ambrevar.xyz/