It's still 2 separate devices. I bought more games across Wii and DS than Switch because they were separate devices. I bought New Super Mario Bros (DS) and New Super Mario Bros Wii (Wii). But I'm not about to buy New Super Mario Bros Deluxe (Switch) twice just to keep up with my purchase rare on the DS and Wii.
You should really look at it from a software to hardware attachment ratio.
Wii - 9.06:1
Switch - 5.9:1
That Switch figure is far higher than either Wii or DS at the same point in their life and already about to pass the DS.
No, at the same point in life the Wii already had a software tie ratio of 7.0 (353m Wii software / 50.4m Wii hardware). One year later the Wii had a software tie ratio of 7.68 (545m Wii software / 70.4m Wii hardware).