I would guess a smaller attachment since I can't imagine a balanced additional rocket stage. It'll need to be pretty wide in diameter and wouldn't be the best way to boost this. Any improper or induced misbalance will let aerodynamic forces create a couple to destabilise the entire thing. If the drone can be taken to the proper speed and altitude using another rocket stage, I think the configuration should be similar to how a shuttle is positioned with the booster rockets.Is it possible that there is an additional rocket stage?
This drone is probably dropped from something unless those attachments on top are fakes to mislead. To be honest the nozzle end here as displayed in the parade do look a bit like they're missing something. It's probably just a cover and they've removed it to show it's rocket powered in case anyone was to assume it's something more exotic. Makes sense since the CCP is an organisation that doesn't usually like letting adversaries thinking too highly of its military ability.