Are my pantry and purchase data uploaded anywhere?

No. Everything pon learns about you — your pantry, your repurchase rhythms, your statistics, your in-store order — is created and stays solely on your device. We don't upload it, don't analyze it, and don't even want to know it. That's our deliberate stance: your shopping is none of our business.

That's exactly why each iPhone learns for itself. Two devices (or two people) can therefore have learned different amounts and show slightly different things — each learns individually from what happens on it. That's not a bug but the price, and at the same time the benefit, of real privacy: because nothing is collected centrally, everything stays private.

(What you deliberately share — your lists with others, or an iCloud backup of your learning data — is separate and only happens when you choose it.)