Debian Bullseye Fully Frozen
lists.debian.org
lists.debian.org
Undoubtedly, the technologically-astute reader will know that it is not possible to verify a PGP signature without also having a copy of the public key.
Debian uses PGP signing pretty extensively, and maintain a keyserver (and separate search interface I used for this) for their keys: https://keyring.debian.org/