Rumpl Puffy Poncho
If Rumpl's Puffy Coat Blanket isn't hands-free enough for you when you need to keep warm and dry and, say, jump up to cheer or your team or pee in the woods, perhaps the Rumpl Puffy Poncho is the wearable sleeping bag you're looking for.
The Puffy Poncho comes with more options for moving around without losing your coverage than the Puffy Coat Blanket, but refrains from forcing you into the same level of onesie commitment as a Selk'bag. Rumpl actually suggests the Puffy Poncho as an alternative to a trash bag, but the two aren't really comparable on any level except the hole on top.
The Puffy Poncho is made from the same materials as their more realistic comparisons, sleeping bags and down jackets, with a waterproof shell on the torso and 3-panel hood. It also has a zipper-secured 'roo pouch on the front for small items - keys, phone, roll of t.p., Boozebrella - plus a media port and key loop inside. Oh, and don't forget the beer koozie pouch up above the zippered 'roo.
Puffy Poncho sides are secured with snaps, which unbutton to flatten it out into a blanket, and the whole garment packs down into its front pocket if a pillow is what you're looking for. Puffy Ponchos come in 2 sizes an 4 different color combos.