This sounds very similar to buying bonds. I’ll use Israel Bonds as an example. You can pay them $100 today and get a certificate that you can redeem in 2 years time for $110. They use the funds immediately and you collect a higher value at a later time.
Small business may not have access to the financial markets that allow them to raise funds in the form of bonds or stocks. I like this idea of gift cards, but it does contain a lot more risk as the gift cards are not underwritten by a 3rd party the same way a bond is.