addlink has come out with an M.2 SSD that is aimed at NAS users, the addlink addNAS N50. While it is marketed around replacing HDDs for a performance boost, its form factor suggests it may be better leverages as a cache in NAS devices (assuming the vendor hasn’t decided to only use their own SSDs). While the drive is aimed at NAS use, there is nothing that precludes users from leveraging the drive in other storage use cases.