The canonical use case here (and it's already a thing) is an iMac running Capture One and/or Phocus (for Hasselblad) and/or Lightroom (if the desired output is

The canonical use case here (and it's already a thing) is an iMac running Capture One and/or Phocus (for Hasselblad) and/or Lightroom (if the desired output is raw + xmp) for tethered commercial photography on set. There are rugged cases available for it. All you need is the iMac, a keyboard and (Wacom) tablet and cable for a rather complete DT (digital technician) setup. You don't need a lot of processing power in the grand scheme of things, you just need something that the photographer, AD and client can use to make decisions without incurring the cost of a potential reshoot. The grunt work of post-processing is done elsewhere and elsewhen - that's much to costly to do on location - but you do need a "close enough" representation of final colour and contrast, along with focus checking, page overlays and that sort of thing.