They are probably limited to suit their true purpose of being floating “screens”, but I wouldn’t mind some additional full zoom capability.
Some games with hard fov limits too narrow for fullvr can better get by in the cinema modes; not only because the image is more zoomed out, but the curve of the screen and and narrowing of the focal point seem to help some as well. There are a few profiles I’ve worked where I wish I could zoom the screen in closer to hide more edge culling or borders, to better fake the fullvr mode.
atm, the most you can do is turn screen curve to max and enable vertical curvature as well (cinema mode). This has mixed results with edge distortion though, depending on the game.