[wintogreen74]

My biggest learning from time in the eCommerce world: trivial-sounding things are very, very difficult to get right, and the edge-cases in api-based solutions are entry-level features.

Take a single one of your items: inventory management. There's SOOO much going on here, people look and say "What's the big deal? decrement an integer!" How do you handle payment failures and dunning management? Subscriptions? Bundles? Incomplete carts? Buy online; pick-up in store? blended inventories? multiple locations? The list goes on and the number of interconnected components makes this really hard to solve.

You're building all this, a marketplace and front ends for web & mobile? With a team of 7? I had a team of 23 and struggled to stay on top of all the nuances in just subscriptions, so you're (a) missing important use-cases or (b) way more effective than my former team. Chances are it's somewhere in between.