Pocketable, foldable tablet with split displays, a pen with haptic feedback and rigid glass screens for stylus use without damage. Modern Android and a great camera don’t hurt and those make the SD2 better than the SD1; otherwise they’re fairly similar besides the accessory compatibility and some halo functions like wirelessly charging my Slim Pen with the magnet case.
I travel a ton, edit spreadsheets at clients site visits and trade shows while I have Teams open on the other screen, and use the stylus to mark up PDFs for architects and subcontractors. I enjoy being almost required to multi-task when I have my phone open, and the Duo 2 is the best phone for multitasking, bar-none.