I saw this complaint in another post online (paraphrased):
The screen and use of a Pi seem at odds with each other. The screen is ultra-low power, but there are of course huge drawbacks for usability. Meanwhile the CPU is very powerful, but chews through, comparatively, a lot of power quickly.
They argued that it would be better to either pair the Pi with a better screen for a more powerful/usable handheld, or go all in on longevity and use some kind of low-power chip to pair with the screen for a terminal that could last for days.
... I've got to say, it's a fair point. A low power hand-held that could run Linux and run for days would be pretty cool, even if it was underpowered compared to a Pi. No idea what you could use for such a thing though.