You can also configure multiple ssh keys through Github subdomains in your ssh conf file. While github ignores the subdomain your ssh-client will pick the corresponding ssh key bas d on the used subdomain in your repo url.
So subdomains can be arbitrary and you just manually add them when performing git clone? Will then git push/pull/etc automatically use the fake subdomain you like for this repository?
So “work-github” can be a Host entry (with a HostName of github.com) and key A. While “play-github” would use key B.