Please direct me to any EVs that actually do this

The Nissan Leaf “actually does this” (though in the UK, it will stop working unless you have a recent model). Obviously it only works if your power company supports it.

It’s relatively common around the world and often has nothing to do with saving money. It’s often about protecting the energy grid. For example in my city the grid can remotely switch off hot water heaters when they are struggling with demand. And at work we have red power points on the wall that have a higher grid priority - the entire city could have a blackout but those power points should still have power. Not because we have a UPS but because the grid will not cut power to that circuit unless there’s a catastrophic safety risk (e.g. the power line fell over and pedestrians are walking all over it - they wouldn’t send power then).

Sometimes that works by cutting delivery but increasingly often it’s done at the consumption side. The switchboard on the outside of my house has a cellular radio connection to the energy provider so they can do these things.

It’s also possible to roll your own off peak system - if you have solar panels on your roof for example you might only charge when your panels are producing power. And you can do that from your EV charger, meaning it will work with any EV.