Firmware available under open source license.
Firmware available under open source license.
Open source firmware exists and is used for various hardware, including storage devices. It falls under software rather than traditional operating systems. This topic is definitely relevant to the field.
You're asking about different types of storage solutions like HDDs, NAS, and SAN. For open-source firmware, Power8 is the best option since it's fully open hardware and source code. If you prefer Intel, a libreboot t60 could be your best bet.
Largely the HDDs are proprietary, though a few individuals have managed to reprogram them. Personally, I don’t perceive a significant security risk, especially considering the encryption involved.