The OXC engine already has multiple zoom levels from the Options > Video screen.
If we need easier and faster zoom in and out for precision, specially in cellphones, it would be great if we could BRING those choices to the Battlescape bottom menu, like a + and - to cycle through the 1x, 2x, 3x etc zoom level.
That would be a first step. Second would be to create a 0.1x incremental/decremental zoom, and tie the mouse wheel to it. Or a pinch movement on phones