No-one forces you to connect your "smart" TV to the network... You can just use it as a "dumb" TV and connect anything on it (such as a Raspberry Pi) to do the "smart" things. I have an old Toshiba smart TV from >7 years ago that I bought second-hand for 100€, and while it is doing great as a dumb TV I would never connect it to the network considering there have been no firmware update for years and that the current one is likely affected by un-fixable security holes !