https://wccftech.com/the-witcher-3-nintendo-switch-has-been-developed-in-12-months-improvements-over-e3-build-detailed/

The Witcher 3 on Nintendo Switch was considered unlikely by many, but CD Projekt RED and Saber Interactive made it happen. And it seems like the port has been in the works for some time.

Speaking with Eurogamer, CDPR’s Piotr Chrzanowski confirmed that The Witcher 3 has been in development for Nintendo Switch for around 12 months.