What makes you think an EEG headband is not just a smartwatch in a different form-factor? We're running an nrf53 plus extra storage. We don't have a screen, but screens are fairly inexpensive. We've got a full EEG system.
We have actually done pretty well at limiting the number of parts. The headband is so thin it's buttonless. We didn't have room for a button and created a fully buttonless interface.
There are parts you wouldn't think would be expensive but are. Bone-conduction transducer, heart-rate sensor, etc etc. Yes, we could ditch the HR and save some money but we feel it will be beneficial.
Watches are a thing that exists. EEG sleep headbands aren't. We had to create our own materials for EEG sensing. Everything else on the market have limited life and aren't comfortable enough for sleeping.
Of course, all the plastics and TPU are custom. The fabrics are custom. Our scale is also very small right now, so I fully expect the cost to come down significantly with scale.
