Is there a feature that lets you pin collections/titles so that even when you change the sort options, they still stay at the top of the collection or library? If there isn’t I think this would be a nice feature to implement.
Yes there is. Navigate to a certain folder and select “favourite” — either by long pressing a collection or by tapping top right.
After you favourite a collection it will appear in the content screen.
Is it possible to pin a title to the top of a collection?
No, unless you manually drag it there which will turn on manual sorting