One Game Launcher provides a centralized place for your game library easily accessible by gamepad, keyboard & mouse, or touch.

* Starting with version 1.2.1.0 the One Game Launcher can be accessed both as a standalone application from the Start menu and as a widget within the Game Bar.

It allows to the user to open the Game Bar overlay by pressing the Xbox button on the controller, or Win+G on a keyboard, and launch a game via the One Game Launcher widget.
One Game Launcher supports various game stores such as Steam, Epic, GOG, Ubisoft, Origin, Battle.net, Microsoft Store, Game Pass, Microsoft Cloud, and allows to add any game, app or URL manually.

Reddit: r/OneGameLauncher

More info:

Use your PC like a gaming console:
What if your PC is connected to a standard TV and you want to use it like a game console? With the One Game Launcher widget, it’s as simple as grabbing your favorite Xbox Controller, jumping on the sofa, and launching a game with the One Game Launcher’s easy-to-navigate user interface. Before, the only way to launch a game on Windows would be to use a keyboard & mouse, which is unergonomic to use with a TV. But now with the One Game Launcher widget, PC gaming can finally offer what console gamers have enjoyed for decades: an easy-to-use game launcher built right into Windows without the need for a clunky keyboard & mouse! Now your PC can be your gaming console too!

PC Gaming Accessibility:
In 2018 Microsoft released a revolutionary product: the Xbox Adaptive Controller. Any user of this controller can connect it to an Xbox console and navigate the system, interact with apps, and play games.
But what if a PC owner wanted to use the Xbox Adaptive Controller due to limitations with using a standard keyboard & mouse? They would not be able to launch a game on PC since standard Windows does not support opening a game with an Xbox Controller (Adaptive or otherwise). Therefore, said PC users are required to use a keyboard or mouse first to launch a game, and only then may they switch to a controller. Here is where the One Game Launcher widget comes into the picture!
It allows to the user to open the Game Bar overlay by pressing the Xbox button on the controller and launch a game via the One Game Launcher widget.

Users can use Settings - Custom Provider to add any game, app, or URL manually.