The batteries for a typical DSLR are around the 1800 mAh hour, not that different from a phone battery. I used to get around a thousand shots out of my Canon 5

The batteries for a typical DSLR are around the 1800 mAh hour, not that different from a phone battery. I used to get around a thousand shots out of my Canon 5D3 per battery; there's a lot of mechanical power and ~25GB of processed data going into that usage. That could be either over 2-3 hours (event coverage) or over days (landscapes). So DSLR battery life isn't really measured in hours. I don't think the batteries need to be better, particularly since you can install a grip to let you have 2 in the camera at once, and it only takes a second to swap them. That said, adding a separate Android subsystem (that doesn't always have an LTE radio on) shouldn't add too much drain. You could easily get 4-5 hours of screen-on time to use for photo editing and processing.