I am selling the products on Amazon since September-2022 (10 months). My observations:

1. You can’t sell anything unless you start advertisement.
2. Ad cost per order is coming to huge - in my case about Rs. 150/- plus tax per order.
3. After Product cost Fixed fees, Referrel fees, FBA Cost or Easy ship shipping fees, my profit is always in negative.
4. I stopped ads since last 4 months. I have received only 6 orders in last 4 months. So effectively, without ads you can’t sell anything on Amazon.

Conclusion: A failed venture.