Consoles are things with interchangeable cartridges. That is pretty widely accepted. So no, I would not count Pong clones that only allow you to play the games in the box as videogame consoles. They're videogames, but not really consoles.
As for the Odyssey 1, it really is a borderline case. On the one hand, it certainly has multiple games, each with different cards. But, the cards don't have chips on them; they just change the way the circuits in the system are read. So is the Odyssey 1 a console? Um... sort of yes (it has interchangeable, different games), sort of no (they're not actually cartridges or something like that).
Anyway, for another presumably very poor-selling console, what about the Coleco Telstar Arcade? All of Coleco's other '70s Pong clones are your usual built-in-games-only things, but the Telstar Arcade actually has cartridges. But given that there are only four carts available for the system (one of which came with it), it has to have done pretty badly... which is understandable, given that it seems to have come out after consoles like the Fairchild Channel F and in the same year as the Atari 2600, but really was a Pong clone with interchangeable cartridges. I have no idea how it sold though.