Where are the photos taken by iPhone camera in the Photos app?

The iPhone has no separate Camera Roll album in iOS18, where you are only seeing the photos taken with your camera. In "All Photos" you will be seeing all photos, the photos you have taken together with other photos you have saved to Photos or synced to your iPhone from a computer.

Your pictures are in the Camera app, lower left or right corner depending on how you hold the phone. The pictures are all available in the app, Photos.

I can't advise you on Android.