There is an unofficial keyboard out already
Nintendo might be onto something great, if their whole “extended the life of the Switch through accessories” plan actually follows through. In addition to the whole “portable/console” angle they could also heavily push good accessories, which they may or may not do with their recently patented Donkey Konga drums and keyboard. Found at the US patent and trademark office, this August 28, 2017 patent involves the aforementioned drums and a keyboard from inventor Hitoshi Yamazaki.
Now, Nintendo has patented an awful lot of stuff, and much of it never sees the light of day. Hell, things that have working prototypes and are fully announced may never see the light of day, like the Wii Vitality Sensor. But with Nintendo bringing Donkey Kong back to the spotlight again with Tropical Freeze, there’s a chance we could see a Konga rendition at some point.
Search 15/687771 [USPTO.gov via ResetEra]