Spot on with sewing and tool repair—those little things turn into big headaches fast if you can't handle 'em yourself. I'd add food preservation to the top of the list, too. Knowing how to can, cure, smoke, or dehydrate whatever you've managed to harvest or hunt is a lifesaver when supplies aren’t coming back any time soon. A lot of folks overlook that, assuming there'll always be fresh food, but that's never guaranteed.
Fire-building in rough conditions is absolutely vital, but I’d say learning how to read the weather and spot changes is underrated too. Old-timers could sniff a coming storm or frost—makes a huge difference when you’re planning shelter or planting. Basic herbal medicine skills also go a long way, even just learning a handful of native plants for common stuff like infections or stomach trouble