In your case, you can find coins in the diner in front of the postcard stand and on the beach to the left of the cactus in the grass. In version 0.5.0, major hidden items/coins will be visible.
Yes, before I wanted to make a game with a system as similar as possible to very old school RPGs, but to my surprise this turned out to be difficult for some people, so I remade the game into an easier version and now there will be no problems, but the risk of getting a sudden “Game Over” is all - remains the same, so almost every player’s choice is similar to “Russian roulette”). So save often.