The real solution is to allocate delegates proportionally to how citizens vote, as is done in Nebraska and a couple other states. This achieves exactly the same purpose as the NPVC but is actually politically tractable.
No state has any incentive to assign its delgates to a person the citizens of the state didn't vote for. You can do what the NPVC does and make it contingent upon everyone playing along, but that requires everyone to play along and is incredibly tenuous. Even if it ever goes into effect, as soon as states allocate delegates to someone who wasn't the most popular candidate in their state they'll pull it, and the whole thing will fall apart.
Every state has incentive to allocate its delegates proportionally. That's exactly what people want. They want that more than winner takes all. It doesn't require a huge chuck of states to buy into it amd it isn't tenuous. But it accomplishes the same goal; if states allocate delegates proportionally to how they vote, then the most popular candidate gets the most delegates. If you're in one of the many states that has winner takes all, advocate to do what the few more democratic states have already adopted and are happy with.