The PDF manual has some answer about the buttons
- Quickly Open Camera: Double-press the Power button to launch the camera from any screen, even when the phone is locked. (This is a standard Android feature and can be checked in Settings → System → Gestures).
- Customize the Power Button: By default, pressing and holding the Power button launches the digital assistant (Gemini or Google Assistant). If you prefer it to show the power off and restart options, you can change this behavior.
- Go to Settings → System → Gestures.
- Tap Press and hold power button.
- Select Power menu. Now, when you press and hold the power button, the power options will appear instead of the assistant.
The moments switch can be configured to either
- Moments (the default)
- there are some presets but it’s possible to configure custom Moments profiles
- Do not disturb
- Airplane mode
- Torch
- Dark mode toggle
- Energy saver
The options for the moments switch I took from this (German) video https://youtu.be/7iDb34aAe0k?feature=shared&t=140