Being able to play AAA games is not a qualifier for a console. My PC can also play AAA games, but it is not a console.
The Steam Deck, and Switch, are both handhelds. It is a subcategory of game console, but it is not considered a game console just the same as a Game Boy is not considered a console, but it is a handheld. Both the Steam Deck and Switch have a screen and internal battery, along with a controller that is built onto the device, like a Game Boy.
A Steam Machine is a Linux PC, but is more similar to a console than the Steam Deck.