There is no single minimum amount required to trade gold across all brokers. The practical minimum depends on the broker's XAUUSD contract size, minimum lot, margin requirement, leverage, and trading costs. Before funding an account, check those specifications and make sure the balance can support your planned risk and stop loss.
A broker may allow a very small XAUUSD position, but the amount needed to trade responsibly can be higher than the technical minimum needed to place an order. The correct starting balance depends on position size, stop-loss distance, risk per trade, spread, commission, and the broker's margin rules. Treat the broker's published contract specification as the source of truth.
Risk note: Do not choose a balance only from the broker's maximum leverage; calculate risk first.