This is the Kickstarter campaign for Astride Bionix's Lex Chair, a ~$250 exoskeletal chair that looks like some sort of climbing harness and provides a place to sit no matter where you go. Alternatively, save yourself $250 and just do what I do and don't go anywhere without ample seating.
You can put it on in half a minute, and pull out the legs in just a couple of seconds. It weighs about 2 lb but can support 264 lb.
Three complaints: 1) I'm pushing that weight limit 2) there's no backrest and 3) your legs are the front legs of the chair! That's no way to relax. If I wanted to be half a chair I would have gone to furniture school and dropped out after sophomore year.
Keep going for a handful more shots and the Kickstarter video in case you need this in your life (no judging, I'm just holding out for a practical, wearable bed).
Thanks to Brett DA, who agrees there's nothing wrong with just sitting on the ground and crying with your head in your hands.