The live view could always be displayed uncropped on the screen. If the phone is held in portrait orientation, the live view is placed at the top of the screen and all relevant controls at the bottom (outside the live view). If the phone is held in landscape orientation, the live view could optionally be placed in the center of the screen with the controls meaningfully distributed to the left and right sides (again outside the live view), enabling 2-handed operation. Or like in portrait mode: Live view on one side (left or right), all controls on the other, which can be more practical sometimes, e.g. when taking selfies.
General question: Should the RAW file always cover the full sensor region (4:3) and only the JPEG be cropped to 3:2, 16:9, 1:1, etc.? Some mirrorless cameras do it like this. In such a case, an additional frame could be placed into the live view to indicate the crop area for the JPEG.
Both make sense IMHO. When zooming to check focus, some kind of picture-in-picture method could be used to easily move the zoomed region around the entire frame (think of “Navigator” views in image editing software).
If you refer to focus peaking: Yes please (in addition to what you called “technical focussing zoom”)! 