Both. Bright SDK for developers can run as an SDK (for software) or as an embedded library (for hardware).
Most of the information presented in this FAQ mentions software provides, but is totally applicable for hardware providers as well. The only difference is in how the code is implemented on the software or device.
If you are a hardware manufacturer (router, IoT etc) please contact us to discuss your platform. Note that we pay NRE fees for implementation in addition to per-device license.