Personally, I'm really excited to see what the end product will look like. Given he does enough trials beforehand, hopefully the purchase would look something like this:
1. Visit website. On the webpage, login and click "order 1-week supply."
2. If you're a new customer, then put in some basic metrics (height, sex, age, current weight, activity level, exceptional family diseases/allergies). Then, a "standard" supply will be shipped to you, optimizing the ingredients generally for what they think you'll need, with an ingredient list (how much of each ingredient is in one serving).
3. When logging in again, you're asked "Are you experiencing any symptoms?" Then, you can list anything that feels off, such as aching joints, cravings, etc. Then, the site would list common deficiencies/overdoses that would cause those symptoms, and give you the option to purchase, for instance, a temporary magnesium supplement, or recommend that, prior to receiving your next shipment, you consume one less serving per day. After using the supplement, you'd input whether the symptom improved, and the ingredient's quantity would be adjusted in your next shipment.
The tricky bit about this system would be personalizing everyone's orders, at scale. But it should be pretty possible (says the developer without an understanding of manufacturing), and for far less than it would cost to order a full meal.