It'd be safer to do firewall blocking, since the TV could fall back to a well known public resolver (i.e. 8.8.8.8) or even do DNS over HTTPS to a known Samsung

It'd be safer to do firewall blocking, since the TV could fall back to a well known public resolver (i.e. 8.8.8.8) or even do DNS over HTTPS to a known Samsung IP. Though blocking is a little harder if you want to use built-in apps of the TV (i.e. Netflix) while blocking it from sending viewing data to Samsung or its affiliates. Though if you really want to keep the TV from spying on you, the easiest thing to do is to just not connect it to the internet (which is still an option in these pre-5G days, not sure that will always be the case in the future, the TV may have a built-in 5G modem that it can use to talk back to the manufacturer)