Ad-Revenue Coin Quiz App -- 3

I want to launch a lightweight general-knowledge quiz where every correct answer rewards the player with in-app “coins” while every game session shows ads that become my main revenue stream. The flow is simple: pick a category (all questions fall under broad Pengetahuan Umum), answer a timed multiple-choice question, see the correct answer, collect coins, move to the next round, and occasionally watch an interstitial or rewarded slot served through AdMob (or a similarly easy-to-switch SDK).

Key things I need from you
• A clean Android build (Flutter, React Native or Kotlin—use what you’re fastest with) that I can later port to iOS if the numbers look good.
• Local question bank that can be expanded through a small admin panel or a JSON import; at least 500 starter questions in Indonesian are included in the quote.
• Coin ledger: each right answer gives X coins (value stored in a constant for quick tweaks). No other earning methods are enabled right now.
• Ad hooks: banner on the home screen, interstitial every N rounds, optional rewarded video to double coins at the end of a session.
• Basic analytics (Firebase is fine) so I can track retention and ad impressions.
• Source code, build instructions, and a short Loom or PDF walkthrough that shows me where to swap question sets, edit coin values, and plug in my own ad IDs.

Acceptance criteria
1. App installs and launches on Android 8+ without crashes.
2. Correct answers increment the coin counter instantly and persist after app restart.
3. Ads display in the designated spots and respect Google policy limits.
4. I can add a new question via the admin screen, sync, and see it live in the next game.
5. All strings and UI elements are in Indonesian; no hard-coded English remains except library defaults.

Tell me your preferred stack and how many days you’ll need for a first playable demo.