The LCD panel ... literally fit in the palm of your hand.
It's cheaper to do a miniature reflective LCD, actual pocket TV LCDs are only used in home brew projectors.
Most of the cost of LCD is area of glass. secondarily the driving electronics. Having 1200 x any number of columns is driven as 2 off 600 x any number columns on on panel. Or even as four panels on one substrate/glass.
DLP for 1080p is tiny, but these won't use DLP, too expensive and needs either 3 + prism or a colour wheel.
Typical full HD LCD on Silicon (LCoS) cells are about 1-3 centimeters square and about 2 mm thick. They are reflective. Larger projectors use three chips/cells and optical combiner.
Whilst initially developed for large-screen projectors, LCoS displays have found a consumer niche in the area of pico-projectors, where their small size and low power consumption are well-matched to the constraints of such devices.
NO-ONE commercially produces projectors based on transmissive pocket TV style LCD panels any more, most of those were only 640 x 240 or less though! Even at 6" Look at the resolution of most cheap "photo-frame" displays, they don't even do 480 lines!