Thanks for the reply. I had assumed SfAutoComplete would compose a new query when the DataSource was set to an IQueryable. I am glad I asked.
I use Realm as my backend, which returns an IQueryable (supports live updates) when I query for a RealmObject (e.g db.All<Tag>() Realm Collection). I would like SfAutoComplete to filter the results by using the IQueryable instead of retrieve all records and then filtering.