They did not have other sizes at launch. If you read the article, the game publisher let slip that Nintendo has started offering smaller, cheaper carts.
My theory is that the Switch 2 launch was rushed. Nintendo had been delaying the system for years, saying that Switch 1 sales where still over performing expectations. Last year, Switch 1 sales fell faster than the Nintendo expected and suddenly they had a system ready to release in a couple months. I would have expected the pre-release hype cycle to be longer but I suspect Nintendo expected the death of the Switch 1 to be much slower.