It's not really surprising that the Switch is doing so well. There are plenty of Nintendo-exclusive games available, but it's also becoming one of the best places to play great quality indie games. While games like Hollow Knight, Dead Cells, Dandara, and Celeste are available on multiple platforms, most developers say the PC and Switch console versions are outperforming other consoles.
The developer of Tangledeep
recently confirmed that Switch sales performance was 23% of lifetime PC sales a month after launch. So it's definitely one of the best platforms for indie developers to gain traction. Especially with how terrible game discovery is on Steam right now.