Nintendo has shown us that the Nintendo Switch Lite is going to surpass Wii U in sales soon, as we saw from the latest earnings report of the company.
As of December 31, 2019, Nintendo Switch Lite had sold 13.53 million units worldwide. Which is so close to the sale count of 13.56 million for Wii U. Considering Wii U is older hardware, Switch Lite will surpass that sale numbers sooner or later.
The original Switch had already sold over 79.87 million units, which already surpassed the sale count of Wii U. Even though, 13.56 million sales at that time is very impressive considering the situation of the gaming industry back then. You can see the other Nintendo product sale counts here.