Firebase Team AMAView other answers to this thread
Do you plan to support LinkedLists? In FireStore? Would be good for managing ordered lists and improve sorting.
Another way to order lists by a specific criterion is to add an artificial sorting key. Let's say you want to enable users to re-arrange their to-do items into the order they plan to work on them (which might not be the same as the task priority). By adding an "order" field and populating this according to the order the user arranged their tasks in, you can implement this use case with Firestore's built-in capabilities.