I also know that Nintendo is actively meeting with independent developers to find new partners. Some of that is around publishing indie games, which Nintendo does from time-to-time, but it’s also seeking studios that could work on some of its IP. Nintendo regularly works with third-party teams, including Bandai Namco, Team Ninja, Platinum Games, MercurySteam, WayForward and Grezzo. But the company is looking to add to that roster, and I know of three studios that are deep in conversation around making games based on Nintendo brands.
Actual Source: Christopher Dring at Gameindustry.biz: https://www.gamesindustry.biz/how-can-nintendo-switch-2-surpass-its-predecessor-opinion
Nintendo has been using third party devs since at least the SNES.