NAS and RTSP, which OS?

What type of NAS OS does Eufy support? I am debating between Synology or building my own. I would prefer to build my own but am unsure whether it will be supported.

Any OS that supports RTSP should work to some degree I have used QNAP and MotionEye. Also have TrueNas, but haven’t tried using Eufy with that OS yet. Different OS have different programs or extensions available to handle security cams. Some, like Synology or QNAP charge a license fee per camera after an initial number of cams.