Very cool. The biggest hurdle is the methods of synchronizing exogenous stimulation with the endogenous stimulation. If you could somehow detect endogenous stimulation using a simple headband like Zeo then this would make the technology very accessible!
Yea, I'm not sure what quality of EEG you would need. Is wave by wave measurement conducted by Zeo in order to determine what stage you're in? Or does it have other methods? I feel you'd wind up needing something like OpenBCI, but it might wind up being accessible in the not too distant future.
Zeo wasn't that accurate, it would only make readings every 5 minutes or so, and you could configure it to take more frequent readings but then it would run through power faster too. To do a Zeo style band with constant readings you'd need both see increases in the capacities of batteries, and even then still use a larger battery (larger headband). Open BCI would be a good platform for playing around with prototypes.