Do you mean “supply chain attack” when you say “side channel”? It would be helpful to know more details about how your device was attacked if it had no WiFi card at all (and I’m assuming no cellular network or other network access as well?)
In case you are talking about supply chain attacks, this post goes into more detail about some of the things we do to protect the digital supply chain: https://puri.sm/posts/protecting-the-digital-supply-chain/