Tried Superfrog in WinUAE, low resolution and single lines (=> 320x256 pixels) in windowed mode at 800x480:
Used the y-slider to scale the displayed area up to the full height of the 800x480-window. Then used the x-slider to scale the width of the displayed area by the same amount (to keep correct aspect ratio).
The auto-bilinear filtering resulted in this:
But as the Pandora's LCD is tiny compared to the screen you're probably just looking at it'll look more like this in the end:
Just to show you how 320x256-pixel games will probably look on the Pandora.