I'm pretty sure they don't brick your hardware, they just permaban you from their network. No more laggy Smash Ultimate netplay I guess.
There is no circumstance in which Nintendo remotely bricks your console.
When you get banned for cheating, you are banned from that specific game's servers.
When you get banned for installing pirated software, you get banned from all Nintendo Switch online services. The console can continue to be used fully offline.