Hobbies that are becoming useful skills again include gardening, of course, but also blacksmithing, farming and woodworking, just to name a few. If you have an interest in these or other skills, you might find it profitable to learn how to do them, not to mention fun.
Learning leatherworking and being able to make pouches, moccasins or other leather items can be a fun pastime, and provide you with practical things you can use yourself or sell and barter with.
Fletching arrows used to be a fun but unprofitable hobby, but as people begin to enjoy the sport of bow hunting again, perhaps there is a niche market for you to sell your finished arrows.
Almost any hobby can be a useful skill in some scenario, and also a way to generate a side income or profitable home business, so if you have been putting off learning a hobby you would enjoy, you can justify it by turning it into a useful skill you can benefit from in the future.