It isn't a new idea. Looks like a modernized great coat.

Great coats were standard issue in European armies through WW2. The great coat was all weather protection and often served as a combination raincoat, sleeping bag, supply pack, ground cloth, pup tent and field jacket. In many places and times soldiers pretty much lived in their great coat 24/7. It was the all-in-one gear of its day.

Typically made of heavy wool tightly woven to increase its ability to deflect wind and shed rain. Features could include a short cape to increase weather resistance, large pockets that would accept supplies, oversize collars to protect the face and neck, sleeves with cuff closures that allowed the hands, sometimes the entire arm, to be pulled into the coat. Some were said to be sized large enough that a soldier could tuck his legs up into the body of the coat. Lacking anything better a soldier would sleep in his coat.

The down side was the coats were not entirely waterproof and they were heavy for the warmth offered. Gaining, by some reports, ten pounds or more when exposed to rain for a long time.

Modern materials, like poly fleece and breathable membranes, should be more weatherproof and less likely to hold any water. They should be about as warm as an equal weight great coat but lighter in wet conditions, perhaps drier, less itchy and more resistant to insect damage.

A modernized great coat is a good idea. A lot depends on details and specifics. Perhaps how you drive it. The price seems high but if it is all that the best great coats were it could be a real bargain.