Sorry for your loss. Fires are tragic, traumatizing events, even when no one gets hurt. Hope you can get your insurance company and agent to quickly rebuild the structure and replace lost contents. As a retired firefighter with a total of over 35 years, with three fire departments, it has been my experience that the sooner you can get the old structure torn down and you can start work on a new one, replacing the contents the best you can,the sooner you can see positive possibilities. One word of hope/suggestion. Even with heavy destruction, if it can be safely done, check for salvageable possessions. Even in heavy involvement fires, there can be areas that did not have as high a heat, or items that are not destroyed beyond salvage. Areas closest to the floor will generally have the lowest temperatures, but also check corners. Sometimes fire rolls the corners and does not burn those areas as severely. Check protected areas inside cabinets, at the back of shelves, etc. too.
You will remember this fire and its impact for the rest of your life. If you can salvage a few items, and clean them up enough to display them in your new shed/workshop, but still show the fire's impact, they can become treasured keepsakes. It is counterintuitive, but it seems to help a lot of property owners cope with the loss in a positive, take control way. It seems like it links the two structures, and makes the new one part of the old.............
Just make sure it is safe to enter each area. From the pictures, there was heavy damage to some structural supports, and a partial collapse. Ask if a fire investigaor or safety officer can come out and determine which areas are safe to enter. If no areas are deemed safe, be there when the demolition crew is working and keep an eye out for salvageable items and keepsakes. A lot of wrecking crews will work with you if you explain what you are looking for.
Mike