I have noticed that Wawa (mid-atlantic convenience store often paired with gas station) is starting to set up a supercharger network, sometimes even when there is no gas station already existing.
Anecdotally, I agree with your assessment that EVs will cause more purchases.
I've never spent more than 5 minutes in a 7/11 in my life.
The point of those stores is to get in and get out quickly. It's the exact opposite of an EV charging station. In fact, most 7/11 in my area enforce the 'no loitering' rule.
I don't even think that 7/11 managers want you there for more than 5 minutes.
Restaurants or shopping malls I'll stay for 2 hours regularly, and a few level 2 chargers can actually get me 50 miles of charge in that time. That's where the EV chargers should be.
Anecdotally, I agree with your assessment that EVs will cause more purchases.