I live in Minnesota and these signs show up in the drive thru of our local BK every summer and disappear every winter. I don’t think it’s any kind of special promotion, probably just an additional revenue stream.
The fountain machines typically have a bunch of ice in the hopper already, I’m guessing any bagged ice they sell is probably pretty high margin and not frequent enough to interfere with the primary business.
FYI, SONY is a Japanese multinational corporation.