I think you would unfortunately need an universal zooming solution for the whole device - I don't think it would help really much if you could zoom the main menu items (which remain the same always, i.e. you can learn the positions by heart) but then you enter an application that has the same size text and buttons as the main menu.

There is no universal solution like that available, and it unfortunately wouldn't be really easy to build in the software. I know some people with problems with their vision use an optical solution (i.e. a big lens or something like that) to help with small devices.