"Bushcraft" is pretty much illegal in designated wilderness areas, where the somewhat misnamed "Leave No Trace" principles reign supreme and are basically the law. No cutting green wood or standing dead wood, no fires at or above timberline, no fires at the more popular lakes.... Right now in the Pacific NW, fires are banned altogether because of the extreme fire danger (and a lot of fires burning right now). Outside wilderness areas things aren't so strict, but the US Forest Service frowns on cutting green wood anywhere. I'm sure there are other areas where bushcraft can be practiced, but it's well to be aware of the local regulations before doing so. Bushcraft can be fun, but if a lot of people do it in one area, it can be destructive of the environment.

Preparedness is far more important. Part of preparedness is having the right emergency gear, such as the "Ten" Essentials. With those, you may not be comfortable, but at least you'll stay warm and dry during an unexpected overnight or two in stormy weather. Another part of preparedness is planning ahead (also, BTW, part of Leave No Trace). This includes such items as studying maps of your route before the trip to identify water sources and camp sites, planning for contingencies, identifying bail-out routes if the trip has to be cut short, leaving an itinerary with a trusted person at home. Another part is learning outdoor skills in advance of the trip, such as maintaining your body temperature ("thermoregulation"), learning to cope with inclement weather, etc. These skills are best practiced close to home, in your (or a borrowed) back yard or at a car campground where your warm bedroom or your car and its heater are available if you mess up.

One thing not always mentioned is that you can go a couple of weeks without food, but going without water can incapacitate you in less than a day and kill you in a couple of days (or less). Unfortunately, we're all told "don't drink backcountry water unless you purify it." In an emergency situation, if the water is polluted (not all sources are), it will take a week to 10 days to get sick from it, by which time you'll be home and close to medical care. So go ahead and drink as much water as necessary to keep well hydrated. That's far more important than worrying about natural food sources--something I wouldn't have to worry about for several weeks in any case, since I have a perennial overweight problem!