Earlier quoted context omitted.
You'd need a pretty substantial battery on account of how much heat it takes to melt filament. Even the Bambu A1 Mini uses ~150W while heating the hot end. I like the idea of a portable printer, though.
It's actually not the hotend heating that's the largest power drain, it's heating the large heat bed. Bambu Lab is introducing firmware features to more slowly ramp up the heat, but I don't need if that could happen slowly enough to not drain a battery.
Oh right, no idea how I excluded that. I imagine it uses several times more energy. Thanks for the correction!