This same process is true for GitLab, GitHub, Bitbucket, etc.
If you have more than about 5 SSH keys on your PC in
~/.ssh/, you need to setup your
~/.ssh/config file so that SSH to GitHub (or other SSH server) uses the correct SSH Public Key the first connect try.
Do this by adding to
Host github.com User git IdentitiesOnly yes PubKeyAuthentication yes IdentityFile ~/.ssh/mygit
If you get owner/permissions error, fix by:
chmod 400 ~/.ssh/config
Create SSH key for Git
~/.ssh/mygit is created with a command like:
ssh-keygen -t ed25519 -f ~/.ssh/mygit
git over SSH instead of HTTP
Set the remote URL to use SSH by (assuming the repo remote is github.invalid/username/myrepo)
git remote set-url origin ssh://github.invalid/username/myrepo
For large numbers of repos, you can pull over HTTPS and push over SSH.