That's my question as well - does EEG have any compelling everyday use-cases that aren't already covered by a heart rate monitor?
I was shocked at how bad the state of the literature was with so many dubious papers, especially since the explosion of ML techniques.
I came from a Physics background and there you could generally trust the literature was legit and not just smoke and mirrors to get published.
I would not put much (any) stock into this. The army has put out RFPs for using magnetic tourniquets to induce clotting without external pressure. With magic. Just because the military pays someone to try something does not mean that it is not entirely bullshit.