Granted it looks like it's for battle simulation only a this point but it's a large leap to hard light this early into.

Lorca having a tribble on his desk a couple of episodes ago was a push, but mildly possible as an uncategorised pet he'd picked up recently but a fully working holodeck with tangible sprites? That's going to need some backstory to explain that one away as something we don't see again until the 1701-D.