Keys association to the controllers input actions

How can I associate keys to the controllers input actions? For instance, how can I simulate the grip button?

The issue names no files, tests, or entry points. Start by locating the controller input-action handling and any existing key-binding logic in the Unity project. Done means establishing whether keyboard keys can be associated with actions such as the grip button and documenting or implementing the required behavior.

Written by the indexing model from the issue text.