Here is something I did. Ignore the other details in the article, and focus on the "SSH Split Personality Disorder" part. This article was written for a 200-ish member team of a Startup and so most of won't be relevant to anyone outside the Company.

https://story.mobisy.com/bulletin/2019/03/08/eagle-eye-ssh-s...

I split the Git Identities based on which directory I'm working on.