It will gonna be a good idea if Nokia target to manufacture it's own Smart Accessories, such as;
1. Smart watch for smartphones (for multipurpose)
2. Bluetooth headset for smartphones
3. Bluetooth speakers for smartphones
4. Bluetooth (for one ear)
5. Nokia power bank (by keeping view in Nokia batteries backup)
6. Otg cables (like other companies have)
7. Storage devices (such as SSD, HDD, Micro SD Card, Pendrives, etc.)
Because Nokia have a goodwill and a great reputation in the eyes of million people & it's still alive in the minds of million people, the people who uses Nokia Smartphones, want their good, long lasting, effective (having more features and durable) and their complete accessories from the mobile manufacturer "NOKIA CORPORATION".
So, in my opinion you must focus on the demand of people what they want. So, they can find Nokia as Caring One and help to grow the NOKIA CORPORATION.