I put together my own army and had so much fun with this. When you recruited a sim they would stand like those stormtroopers with pistols and behave like one. I had a sim who was top rank first order (two sims actually) and outside of Batuu I could still use certain interactions I earned like "check I.D" or recruit to first order" and a few others.
I wanted one too! There is no way as far as I know ☹☹ infact it seems the ability to have your own stormtroopers outside of Batuu has been removed.