YES you can watch LIVE free to air channels on the Fetch MINI WITHOUT plugging in an Antenna.

How can I watch TV without an antenna?

If you don't want to use an antenna, there are several ways to stream your local network channels. The best options to stream local ABC, NBC, Fox, and CBS are Hulu + Live TV and YouTube TV. They both offer a way to live stream major broadcast networks in nearly every market in the US.

Does fetch work on WiFi?

Fetch is delivered by broadband, so as part of setting up you need to connect your Fetch Box to your modem. You can use Wi-Fi to connect if you have reliable Wi-Fi in the room with your TV and Fetch Box. You'll need a Fetch Mini or Mighty (3rd Generation Fetch boxes or later) to set up Wi-Fi.