Yes, it is a potential renegade device on your network, similar to IoT devices or a computer of unknown origin. Modern SoCs are computationally capable, cheap, and would easily fit inside a commodity consumer switch.
I stick to well known name brands. And in any case, it remains critical to robustly secure all your devices even if they are on your “secure” LAN.
It is impossible to know if this is Ethernet via the photos. “RJ45” style jacks are used for numerous applications.