Android Marketplace App Development

I need a complete Android-native marketplace app built from the ground up. The goal is to let multiple vendors list products while customers browse, purchase, and track orders in one seamless experience.

Scope
• Plan and refine the overall user flow for buyers and sellers.
• Design an intuitive, modern UI that follows current Material Design guidelines.
• Build core marketplace modules: product catalog, vendor dashboard, cart and checkout, order management, and basic analytics.
• Implement a clean, well-documented REST or GraphQL API so the mobile front-end remains fast and future-proof.
• Include an admin panel (web or mobile) where I can onboard vendors, approve listings, run promotions, and review transactions.
• Provide full source code, build instructions, and brief hand-off training.
• Assist with Google Play submission and one round of post-launch bug fixes.

Tech preferences
Kotlin or Java for Android, backend in Node.js, Laravel, or similar—happy to hear alternatives if they speed development or improve maintainability.

Acceptance criteria
1. All primary buyer and seller journeys work smoothly on physical Android devices running 10+.
2. UI passes standard accessibility checks and device-size responsiveness tests.
3. Codebase compiles without errors and is accompanied by setup documentation.
4. Transactions process in my test payment gateway sandbox without failures.

I’m aiming for a polished MVP first, then iterations for extra features once we gather user feedback. Let me know your proposed timeline, any similar apps you’ve shipped, and which tech stack you’d prefer for the backend.