It is said that for settlers traveling to Oregon (yes, I know), teachers were put in the "useful professions" category along with farmers, as opposed to less useful ones like bankers.

• Carpentry has already been said.
• Gardening/farming has already been said.
• There are lots of auxiliary skills/practices to horticulture itself. Seed saving, composting/soil amendments, landscape design, [conservation-minded] forestry, the list goes on.
• Food preparation and preservation. Someone's going to have to be able to cook the food that's grown, and probably without relying on the grid. It's way more efficient when you have one dedicated person doing it rather than assuming everyone will just process their own.
• Masonry would be just as useful as carpentry. This might lean towards cob/adobe masonry as it can be done anywhere. Buildings are going to need foundations, and many of them (especially "up north") will probably need masonry heaters to do the job of a furnace.
• Weaving. Fabric will be needed, probably in massive quantities. There's no doubt about that.
• Graywater systems and/or aquaponics are great things to have.
• Electrical wiring, biodiesel and wood gasification, metalworking, and small engine repair will all make the difference between living in the equivalent of the 20th century vs. the 18th or 19th. Solar installation and maintenance probably fits in this category too.
• Distilling alcohol is actually very important. By 30% you have hooch, by 50% you have a solvent that's good for making extracts, by 70% you have a rather good sanitizer, by 85% you have fuel.

Again, don't forget that we need social skillsets just as much as physical skillsets. Prioritizing material technology over social technology is a large part of what got us into this pickle in the first place. If I was laying down the principles for a commune, one of them would be that everybody has to pursue a material skill AND a social skill. But social skills are probably another effortpost.