With a source-only .changes file that targets experimental:
$ dgit push-source -C .../foundry_1.2~beta-1_source.changes
Format `3.0 (quilt)', need to check/update patch stack
curl: (6) Could not resolve host: devuan
dgit: failed command: rmadison -asource -sexperimental -udevuan foundry
Successful workaround: in ~/.gitconfig,
----8<----
[dgit-suite "experimental"]
distro = debian
---->8----
Possibly related to
<https://salsa.debian.org/debian/distro-info-data/-/commit/3e5c7387e4291a55e0fbee08d46507516fe96d76>
and
<https://salsa.debian.org/debian/distro-info-data/-/commit/6bdc3127f0e9e746e305492e36f15128584f8d0b>
in distro-info-data, which configured distro-info-data to reflect that
the codename of Debian experimental is rc-buggy, but Devuan also has an
experimental suite, and theirs has both suite and codename set to
experimental.
Even if Devuan had a dgit server (which as far as I know they don't), I
think most Debian developers would expect an upload to the experimental
suite to go to "our" experimental, not Devuan's.
smcv