Probably not worth extrapolating but a historical curiosity nonetheless.
http://www.nintendoworldreport.com/news/61506/splatoon-3-inks-opening-weekend-sales-record-in-japan
Splatoon 3 has dominated the Japanese game sales charts with historic numbers.
Nintendo have confirmed that opening weekend sales for the shooter sequel totaled 3.45m units - the largest opening weekend game sales in Japanese history. Digital sales were included in the total.
The previous Switch record was held by Animal Crossing: New Horizons (1.88m physical according to Famitsu plus no more than 750k digital sales), while the previous best opening weekend was the 2010 launch of Pokemon Black and White which combined to sell 2.63m units. Splatoon 3 has managed to sell roughly 2/3 of the lifetime shipments of the Wii U original already.