Hey @Nhan_Tran - thanks for reaching out. Based on the flow you described, District does fit the definition of a sales channel, but sales-channel status alone doesn’t always permit an offsite checkout.
For public apps, buyers currently need to complete their purchase through the merchant’s Shopify checkout using a cart permalink or Storefront API-powered flow. Creating the Shopify order after checkout on District would still likely conflict with App Store requirement 1.1.2. There’s a similar clarification from my colleague Kyle in this thread.
If keeping District’s checkout and auto-charge flow is essential, your best next step is to continue with App Review or Partner Support and ask whether a separately approved arrangement is available. There isn’t a standard public-app path I can point you to for that architecture today.
You can find the supported sales-channel architecture here: Apps as sales channels
Let me know if I can clarify anything further on our end here, hope this helps a bit.