As it turns out, there’s this thing called the "half Christmas tree" which is exactly what you’re thinking—it is literally a Christmas tree that is vertically sawed in half to save space and to help the lazy people minimize decoration.
Wall Christmas Tree- when you don’t have room for a full tree! Fold two strings of garland in half and flatten the branches on one side. Hang both on the wall on command hooks - one a few inches lower than the other. Secure the 4 end pieces to the wall with non damaging tape. Decorate as usual.