Yes it's possible to do that on Porter. When you deploy an application, you choose which branch you want to deploy from and we build/deploy the application on every push to the specified branch. Under the hood, we write a GitHub actions file in your repo, so it's completely flexible and up to the user to configure how branches map onto environments (i.e. whatever is possible on Github actions is possible on Porter).

We also plan to support a more out of the box behavior by adding integration with GitHub's recent deployment feature: https://docs.github.com/en/rest/reference/repos#deployments