have at it!

taken from Gitlab's manual page for creating a key, but i wonder what else could be done to expand on it.

#~/.gitconfig
[includeIf "hasconfig:remote.*.url:https://gitlab.com/**"]
path = /path/to/gitlab.gitconfig
[includeIf "hasconfig:remote.*.url:https://github.com/**"]
path = /path/to/github.gitconfig

#example gitlab gitconfig from the included path
[user]
name = Your Name
email = 0000000-YourName@users.noreply.gitlab.com
signingkey = 0000999988887777

[commit]
gpgsign = true

if all works well, Git should be able to automatically use the selected key depending on the repo's stated remote server.