Right now it's not available - I talked to our product manager over workspace, and there's no timeline to include although they do want to address it. In the meantime, I would recommend upvoting this idea: Bring Bot Pages and Metrics into Workspace Analysis
If you are dead set on getting bots as a dimension, you can talk with your account manager to set up a meeting with engineering services. They can create a VISTA rule that would detect any bot hits and populate the backend column into an eVar.
In Adobe's Bot help article - Bot Rules - it states that bot rules "remove traffic that is generated by known spiders and bots from your report suite" Given this statement, there is not any Bot data to assign to an eVar or prop.
That raises the question of how is there data for the Bots Reports. The article goes on to say that the data shown in the Bots reports "is stored in a separate repository for display in the Bots and Bot Pages reports."