Is there a way to export or synchronize Reminders tasks to Todoist?
This is not possible within the App itself. Although you can download an App called IFTTT, it connects the Apps you use and make them work together.
Hope this helped you out!
Todoport allows tasks migration between Wunderlist, Asana, Google Tasks, Toodledo, Trello, Todoist, and Apple Reminders.
However the app is not free, it costs $5 (for as many exports as you like).