The Gas Station is a tool allowing developers to sponsor the transactions of their users. It can be used to facilitate user onboarding, or to implement a specific economic model (e.g., users can mint a NFT freely, but pay a fee when reselling it) which does not need the user to possess tez.
The Gas Station would typically be used by video game developers to subsidize activities for users. It does not require these users to do any transaction or reveal their account, as the Gas Station account independently processes those transactions. However, it's important to note that this workflow may necessitate the use of specific smart contract patterns, such as permit (TZIP 17).
Currently, the API URL for Ghostnet is: https://ghostnet.gas-station-api.marigold.dev. The Gas Station is not yet available on the Mainnet.