> git/GitHub/gitlab/codeberge

Is this about commit signing? Git and all of the mentioned forges (by uploading the public key in the settings) support SSH keys for that afaik.

git configuration:

gpg.format = ssh

user.signingkey = /path/to/key.pub

If you need local verification of commit signatures you need gpg.ssh.allowedSignersFile too to list the known keys (including yours). ssh-add can remember credentials. Security keys are supported too.