Ok, cool. So, the questions that I'd anticipate from merchants are: how do you make money? What do I have to do? What do customers have to do? Unless it's super easy (for both) and doesn't require new POS or someone to register their credit card or payment method, it's slow going.
For me, the revenue from my friends angle always conjures MLM, ie, you are just recommending this merchant so you can earn some cash, which brings down the value of the recommendation, IMO.
Start with the merchants you shop at and get them to try it and give you feedback. Build one at a time until you have momentum to scale.