What we need from you

Chain: our users' wallets and our whole flow are on Solana today. Can you support Solana? If you support Arbitrum only, tell us how cards and buyback work for a user who holds an Arbitrum wallet that we create for them.
Test environment: a sandbox or testnet, plus a dev key.
Auto-open: most users open right away, but prizes and unclaimed packs can wait longer. Can auto-open be configurable, or turned off per purchase? 24 hours is too short for prizes.
Webhooks: polling is fine to start; we'd like webhooks for paid, opened and delivered.
Shipping: we need physical redemption. Is it in scope for the 20 Oct launch?
10% fee: how is it applied: built into the pack price, or a separate transfer to the NR/Tria fee wallet?
Idempotency: can purchase creation take an idempotency key, so a retried call never buys twice?