My understanding is that the only vehicle for which both the vehicle and the necessary house-side equipment are _currently_ available on the market is the Ford Lightning. Several other manufacturers have promised that their vehicles will support it, but there isn't yet any available source of the house side yet.
I assume this means that no one is using open standards or else you could conceivably just use the Ford Lightning equipment with any other vehicle.
The Quasar 2 bi-directional charger has been on the verge of coming out for years now but still isn't ready to just go out and buy it.
I agree with you though. I work from home and so my EV sits in front of my house for the vast majority of the time, and the battery is more than 2x my total usage during high cost hours. I don't have solar, but I do have time of use rating, so if I could use the giant battery to demand shift, that would save me a ton of money every year.
I suspect the main issue is the north american 2 split phases+neutral design.
Specifically, without the neutral, the car can already generate that with the onboard charger. A bidirectional charger costs no more than a unidirectional one if you are designing it.
But generating that neutral is expensive. You either need a hundred lbs of transformer, or some expensive power electronics.