Allowing users to add SSH keys to their account works well for developers to be able to access the repository from as many machines as they need. However another similar use case is the need to deploy a private repository (not available anonymously over HTTPS) to a server as part of an automated script. It would be ideal if you could add SSH keys to a repository itself (rather than just to a user) - that way you could add deployment SSH keys to a repository to allow it to be deployed to a particular server.
The expectation is that you create a "Bot" account, and add keys to that account.
This allows you to apply permissions more selectively, log different actors, etc. Will this work in your situation?