New to Tablo 4th gen

Do I have to have a fire stick or Roku to watch tv with Tablo 4th gen?

You need to download the Tablo app for whatever device you are using for playback…

So if you are using the OS built into your TV for playback, it depends on which OS that is (i.e. Roku, GoogleTV, etc.) as to whether the Tablo app for the 4th gen unit is available for it.

No… Chromecast with Google TV works too as fo phones and tablet