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.
[0] https://www.rtings.com/tv/tests/ads-in-smart-tv
[1] https://i.rtings.com/images/reviews/tv/tcl/s405/s405-ads-lar...
I retract my statement.
Edit: I purchased a 2019 TCL 50S425 and also don't see any ads...
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.
This is not a rationalization for garbage design, but at least it isn't as much of a black box as people might think.