Since you are already working on being able to sort cards via drag and drop manually, I thought I could add a useful suggestion on top.
The idea would be to be able to sort the cards manually and then create a view where these cards are sorted in a certian way.
Let me explain by an example. Say we are taking notes of some recipies. And we now want to sort them manually by how tasty these recipies are. We’d sort them by dragging and dropping them around and additionally create a new view here:
Let’s name it “Sort by tastiness”.
Supernotes would then always show the cards the way we organized them as soon as we click the “Sort by tastiness” button.
After a while we decide to create a new view called “Sort by speed”. We’d organize the cards in the same parent cards (recipies) but by how fast they can be cooked.
That way we can switch between different views and are not forced to have the cards sorted in one way only.
At this point I’d also recommend a “default” view. If no new view is created the manual sorting of the cards will always be default as soon as a user decides to create a new one.
If you decide to add this feature it could be an advantage to be able to choose where those user created views are shown. Maybe a certian view should only be shown in a certian parent card in order to keep things clean. In our example: Only showing the “Sort by speed” and “Sort by tastiness” views in the parent card “Recepies” and all its childs.