An "old" method used to be to put individual items on notecards. These could be rearranged repeatedly, with additional cards inserted as ideas were either fleshed out or fit into a larger context.
It's writing, but not (yet) writing a linear, not to mention final, draft.
I understand that these days some people work in a similar fashion, but with Post It notes. The advantage being that you can spread them out over a table or wall or similar (walls are then a convenient source or otherwise unoccupied surface area), and they won't be as easily inadvertently jostled out of order.
If you are worried about losing a card organization scheme, when they are laid out in such fashion you can take picture(s) in order to preserve a record. This can also serve as a backup mechanism against losing the cards.
It also works for handwritten notes. You do not need to spend a lot of time on the pictures if that time is not productive. But the pictures are so easy to take -- one can just snap them at the end of each day or workday. If your 4 year old randomizes your stack, or you forget your notebook while juggling 3 other things, all is not lost. If that never happens, all you've lost is a couple of minutes' clicking and some non-volatile memory capacity.
Behind all these comments, is the fact that for me, writing long hand is still sometimes most productive. If the volume of output is less, the concentration tends to be higher. And it can be accomplished most anywhere, at a moment's notice.