The article is absolute trash for not mentioning this. “Their iconic keyboards…” is the closest it gets to describing them.

Thankfully, there is a link to the patent at the end.

Abstract

A keyboard comprising a plurality of transparent keys. In use, the keyboard is attached to a device such as a mobile device, to overlie a display screen of the device. One or more images displayed on the display screen are made visible to a user through the keys, which may be pressed by a user. User input is determined by identifying a pressed key, and the image or part thereof visible through the key when pressed.

Basically a detachable keyboard of transparent material as a display overlay, providing tactile feedback while the LCD allows for backlit and customizable key labels. I don’t remember seeing a practical implementation of this IRL or in media but I might be too young for that.