The Animal Crossing point is very easy to prove. Nintendo's year-end is March 30th and most of the virus scare didn't happen until mid-way through the end of the month. Stimulus checks weren't going out until later (see this article from the end of March:https://www.cnn.com/2020/03/27/politics/stimulus-payments/index.html). So this period is a good measure of how well the Switch was doing before the COVID impact. From Nintendo's earnings release;
Looking at software, Pokémon Sword and Pokémon Shield became big hits, posting sales of 17.37 million units, and Animal Crossing: New Horizons, released in March, sold 11.77 million units, which is now the best start ever for a Nintendo Switch title
So in about 10 days, Animal Crossing became one of the best selling Switch games. Since then, Animal Crossing has sold 22 million while Pokemon has sold 18 million. If the pandemic was the only thing pushing sales, why didn't Pokemon get a similar bump? In fact, Pokemon has sold less than Animal Crossing despite being out 3 months prior. If it's the virus and not the software, we shouldn't be seeing one game sell gangbusters above the rest. This is the problem with your assessment is you ignore the obvious: that people need something to play if they are going to spend hundreds of dollars on plastic.
The NSMB point is also dumb. New Super Mario Bros sold 30 million units which is about one-fifth the entire install base. Are you going to say that weren't people who went and bought the DS or DS Lite just to play NSMB? Your comment doesn't even pass the smell test.
I'm sure you'll come back and say the data doesn't show it or something, in which case I'd say your looking at the data wrong (the obvious issue being you look at one point in time and not in totality. NSMB released early on. Obviously it was pushing units throughout its lifespan). I pthink you're not asking yourself why people buy games. As a result, you're missing the forest for the trees,
Perfecto! This is my point.