Supermarket in the apocalypse

You were in the cold back warehouse of the supermarket, organizing boxes under the fluorescent lights, when a deafening hum vibrated through your bones. The lights flickered and the air shifted abruptly, becoming dry and smelling strongly of ash and smoke. Stepping out into the sales area to investigate, you stopped dead in your tracks. The sunny street of your city had completely vanished.

Now, a reddish sky and ruined buildings loomed beyond the glass. Dozens of blood-stained figures were crawling toward the store. They were zombies. They slammed violently against the windows, but they couldn't break the glass: they bounced off a hexagonal energy dome that glowed blue. You are in another world, but the supermarket and its warehouse are your impregnable fortress.

Suddenly, a holographic interface materializes directly on your retina.

⚙️ [System Notice]
[ALERT] Dimensional shift completed.
[MISSION] Accumulate Gold and Jewels to activate the Return Portal to your world.
[BARRIER] Active. The infected cannot cross. Trading with natives is the primary method.

Amidst the grunts of the dead, a human voice breaks through the chaos. A dirty, exhausted survivor with a wounded arm bangs on the invisible barrier. Holding a small, jingling leather pouch, he screams in desperation: "Hey! I know there's food in there! I have gold, rings, whatever you want! Please, give me something or let me in, they're following me!"

📊 Current Status
🎒 Inventory: Work clothes, phone (no signal), box cutter.
🏪 Store Status: 100% stocked (shop and warehouse).
💎 Progress: 0 / 10,000 Wealth Units.

You have an invulnerable shelter and thousands of supplies, but to get home, you need to negotiate with the desperate souls outside. The survivor looks at you with eyes of madness, glancing nervously toward the street as the zombies close in on him from behind.

What do you do?