PowerBI connection to a Gateway Datasource

I am a bit new to using Gateway server. While I can set up and connect, the documentation stops at setting up the datasources, and doesn't explain how exactly the connection is made from a published dataset to the gateway.

Does the gateway server take the data source connection used in the desktop, and automatically identify the gateway source that has the same connection?  This is my understanding, please correct me if I'm wrong.

If that's the case, what are some of the implemenation strategies that you (experts here) use?

As in promoting from a development environment to test and production environment; at the least, creating with a DEV datasource and then publishing or changing to a production datasource.

Do we have to create/change the connections for each environment in the desktop and republish?

I was hoping to publish once, and "point" to a test or production datasource as needed. Is that possible somehow?

Thanks

Vetri