Hi,
I assume you are talking about the raspberry Pi version. Yes, it would be possible to use the Raspberry Pi without wifi, only with the ethernet port. But there are two issues at this moment:
first, I don’t know if I may distribute the image for the raspberry pi version, because of the google’s terms of use for the Android Things. Because of that, I’m not sure that the version for Raspberry Pi will be published at all.
Second: Unless you attach a screen to the raspberry Pi, you will have to use a smartphone to controll it, and then you will have the same problem because the wifi…
Regards…