Echo Plus Zigby Hub as JUST a Relay?

A friend is sending us an Echo Plus as a gift (already on the way) and it includes a Zigby hub. I have an ST hub so I don’t really need the hub and ST controls all my devices. HOWEVER, it dawned on me that where this Echo will be is midway between the ST hub and my most distant Zigby devices (two Samsung Multipurpose sensors).

Does anyone know if this unit will work as a Zigby relay if I don’t use its hub feature as my hub? In other words, can it just exist to be a relay and nothing else (other than the Alexa functionality that is)?