I want to use a GPG key instead of an SSH key. Looking online I found several guides on how to do it. But these guides are about using GPG for convenience. I instead want to know the pros and cons from the security perspective.
Firstly looking at the archlinux wiki:
gpg-agent has OpenSSH agent emulation. If you already use the GnuPG suite, you might consider using its agent to also cache your SSH keys. Additionally, some users may prefer the PIN entry dialog GnuPG agent provides as part of its passphrase management.
I see this post talking about why we should use gpg to sign commits for git. Looking around, I see several guides on how to use GPG keys for SSH access.
In addition, there is apparent reason for people to to have GPG and SSH keys to be interchangeable since GPG has specifically made a command for it.
See here for GPG post on exporting ssh keys command.
See here here for StackExchange post on interchanging ssh and gpg keys.