I’ve heard that if you use the convenience store’s app, you can just take one and“save” the extra item for free pickup at a later time. Never verified it myself though.
Then again, is food is inflating faster than the interest rates, then you could still come out ahead!
Unless you're not coming back for months, the "interest" you lost is under one cent and not worth worrying about
It's also quite a "safe" loan to have because not only is it free to hold, you're probably never going to need to repay it all at once.
???
How is taking both items home, possibly wasting one, better than taking one home, and taking the other in a few weeks and having no wastage? You're just hurting yourself (by possibly wasting an item) just to deny business some fraction of a cent worth of interest, which in ironic given that convenience stores are high margin businesses and you're choosing to buy from them in the first place. Whatever margin they made on the sale far exceeds any "interest-free loan" you gave them.
There's a reason so many companies like to make it easy for you to top up some kind of prepayment account or otherwise hold benefits for you. Not only is it a free float, but it keeps bringing customers back.