Samsung S-Pen is a completely game changer for Galaxy series. Its Bluetooth enabled and can be used as remote control to navigate gallery, taking pictures, browsing PowerPoint presentations. The company tipped its plans for the S-Pen SDK when it launched the Note 9. As a refresher, the S-Pen SDK has been finally released by Samsung for developers and programmers so they can take advantage of its Bluetooth ability in their apps as well.
You can find the link to the official documentation here. You can use it to design your apps around many features. Like you can connect accessory devices to Samsung. You can implement new features related to camera or photography using SDK in your app. You can also program specialized widgets for extended functions for the Android view system. You can collect motion information from the device to use it in your app. You can run multiple resizable applications simultaneously. Or you can you use S-Pen, to take handwritten input to develop applications.
According to official documentation: Accessory SDK allows you to connect accessory devices to Samsung smart devices. With Accessory SDK, you can define a new service between the accessory and smart device, enabling you to use the various smart device functions from the accessory device. The service is compatible with various connectivity environments, which makes accessory development efficient and convenient.
Accessory SDK adds new functions to the service as Samsung smart devices improve. Future updates will enable the accessory and the smart device to exchange more information and support more interworking. Pen SDK allows you to develop applications, such as Samsung Notes, that use handwritten input. Pen SDK uses pens, fingers or other kinds of virtual pens for input and makes it feel like you are actually writing on a notepad with various useful editing functions.