So my Switch has been on for seven years? Neat.
Unless its battery is completely flat and it's not connected to external power, yes, some of its components are always energized for the entire duration of the system's lifetime.
Even in "powered off" state (which in reality is just another power state as far as the hardware sees it), enough circuitry is still active to respond to the power button being pressed to transition to another power state (i.e. "wake up"). It's not a "hard" power button that connects or disconnects a power circuit. It just sends a button press event (short or long) to some tiny microcontroller that always has power.
The Switch has other power states, including "deep sleep" (which is probably what you're thinking of when you say it's turned off in your dock most of the time), "light sleep" (screen off, OS suspended but in a working state, WiFi radio available but not necessarily connected, etc.) and "alive" (doing stuff, playing games, etc.).
In particular, the unit can still download updates and notifications in "light sleep." Enough of its brains are alive to periodically crank up WiFi (or LAN if docked) and ping Nintendo to check, and transition back to "active" if needed. I forget whether it can pull OS updates in deep sleep or not, but it wouldn't surprise me if it didn't still wake up every couple of days for a quick check.
New phones don't even do that, the "power button" just launchs voice assistant and you have to do a
button command to get the prompt to turn it off
In my experience it just wakes up or turns off the display unless you long-press it, which (on my Samsung at least) pops up a prompt offering options like "power off," "reboot," "sell your soul" and so on. Knowing Samsung though I'm sure there's an option to turn on that Bixby shit and glue it to the power button
