Yes. All very straightforward in container station.
First of all, you will likely need to use multiple network adapters on your QNAP. That’s really the cleanest. First, in Container Station, you set up the NIC to be in Bridge Mode.
Then in Network and Virtual Switch first set the IP for the adapter you want to use for PiHole to 192.168.33.0/24. Then you can assign what devices on the virtual switch you want assigned to that NIC.
Now, if you don’t have enough NICs in the NAS, I’m sure that NVS will allow you to route traffic between the different subnets but that really is more of a job for the router.
Does this help?