To clarify because this is confusing: The AirPods work as regular old BlueTooth earbuds on other devices already. This is an implementation of some of the extra features and interfaces that are integrated into Apple products.
How is it confusing? The top of the README explains it.
> LibrePods allows you to use AirPods features that are exclusive to Apple devices. It implements the proprietary protocol used to exchange data between AirPods and Apple devices
> LibrePods allows you to use AirPods features that are exclusive to Apple devices. It implements the proprietary protocol used to exchange data between AirPods and Apple devices
And then has a table listing the features.