The OpenPuck project allows the Steam Controller to emulate console controls, among other uses

A work in progress, but a very intriguing one.
XDA Developers on MSN

This open-source puck lets you use your Steam Controller on Xbox, Switch, and PlayStation consoles

It's cheap to build, too.
Hackaday

DIY Steam Controller Puck Offers Xbox, Switch, PlayStation Emulation Modes

Valve recently released a new version of the Steam Controller, which features a wired USB puck that serves both as charger ...

Enthusiast project turns the Steam Controller into a cross-platform gamepad

Valve's new Steam Controller doesn't natively support XInput, even though XInput remains the standard for many PC games and ...
The Escapist

Steam Controller: Expected release date, price predictions, specs & features

The Steam Controller is Valve’s second attempt at a gamepad built exclusively for PC gaming. It’s due to be shipped as the OEM model included with the Steam Machine and will be compatible with the ...