A product that is "Business to Business to Consumer".

It was a loyalty program for restaurants. I had to sell to the restaurants (B2B), but the main user was their customers (B2C).

I guess this is something like a CRM, where you're primary customers are another business, but you're building something that's visible to their customers, so you're also trying to satisfy these end users.

Never seen the term used before, but pretty sure it means Business to Business to Consumer i.e. they are a business that sells consumer facing software to other businesses. Example would be a POS (Point of Sale) system which I am guessing based on above anecdote is the family of software grandparent was referring to.

With respect to the supply chain; business to business to consumer.