Those packages are provided WITHOUT ANY WARRANTY and only for testing purposes before being uploaded directly in the Debian archive.
Please do verify the signatures on the packages before applying, as there is
no Secure Apt here.
dget(1) should do that
for you, provided that you have my key in your GPG keyring:
A copy of my key is also available in the debian-keyring package, and can be added to your personal keyring with:
gpg --keyring /usr/share/keyrings/debian-keyring.gpg --export firstname.lastname@example.org | gpg --import
Note that you can find any number of packages here, and any of those can be removed at any time without prior notice. It is likely, however that those packages would then probably end up being uploaded to the main archive anyways, in one form or another.