It is technically feasible that any networked Samsung device with wireless connectivity (so, for example, any Samsung smartphone or tablet) have code to allow other Samsung devices to use it as a bridge to reach the Internet, for example by having an unlisted WiFi access point or some kind of backdoor access (for example, using "knocking" to open a supposedly password protected WiFi access point), when they can't directly reach it.

That doesn't just mean stuff you own, it means your neighbour's Samsung devices or the Samsung devices of anybody passing by outside on the street - basically as long as they're in radio range of your own Samsung devices they can silently communicate.

Now, I don't know if this is indeed the case. It's certainly technically feasible (not even hard if all they do is have their WiFi supporting devices have an unlisted WiFi access point), Samsung sells so many devices which qualify that coverage would be pretty good, they very explicitly encrypt their code (so are explicitly hidding whatever is in their code) and given the price and features of most Samsung devices the additional hardware cost to add such a feature would be miniscule (if any cost at all since for sufficiently powerfull wireless networking hardware it's just software that needs changing).

This is without going into more complex stuff such as mesh networking or post-and-forward messaging chaining Samsung devices until one connected to the Internet is found to exfiltrate data and receive remote commands.

Frankly, the one thing I can think of that makes this less likely is that the vast majority of people connect their Samsung stuff to the Internet directly and let Samsung watch them as much as they want, so it's probably not worth the trouble for Samsung to have this kind of thing implemented (though the unlisted WiFi access point thing is stupidly simple) for the handful of people who actually worry enough about privacy and are technically aware enough not to connecte their smart devices to the Internet.