Top up seller pool
When airdrop NAT runs out, buy pool credit with Test-Pi (Pi SDK sandbox). No Stellar wallet required for this step. NAT stays utility for the marketplace motor — not a speculative trade.
Sign in to see your pool.
Pay with Pi: real Testnet / sandbox Pi payment → then pool is credited.
Simulate only: no wallet charge (dev fallback).
Utility rate: 1 Pi = 2 NAT (app peg). Target reference 10 NAT ≈ 1 USDC. Not a market-price promise.