Earlier quoted context omitted.
TCL Roku is pretty "dumbish". You can install it without an account, plug in an antenna and go to town. You can even connect it to wifi then use Youtube or Netflix. Haven't seen any funky ads. My only peeve is that the controller doesn't have a full number pad which makes it a little derpy for the older generation.
My only annoyance with TCL is that once you connect it to the internet, and then disconnect it, the activity light (a quite bright, white light on mine) will flash constantly. Forever. Solvable by tape, but doing that blocks the IR sensor.
Nice thing about OpenWRT is being able to block homescreen ads when the TV is online with the adblock package since DNS filtering will do the trick fortunately.