Nobody asked me to do so, but all my setup (SSH auth, encryption, password manager, mail signatures) is build around GPG, so it was easy to add the signing in my git config.
I use a RSA8192 key as master key so it can last for a while. Then I have RSA4096 subkeys for signature, encryption and authentication. All subkeys are on my Yubikey configured with touch to operate. So when I am on a computer, I plug my Yubikey in there, and whenever I want to do a SSH login, a git commit signing, a password access (pass), a mail signing or anything else GPG related I have to touch my Yubikey.
The setup of such system is not so trivial, but once it is done it is working really well. My digital identity is build around my GPG keys, and they are stored safely in my Yubikey, and to operate them I have to be physically there and press it, so it can not be used remotely if my computer is compromised.