Referencing the _environment URL parameter in a public app to get staging or production version of the app

We are looking to reference the _environment URL parameter in our retool app via the public link to switch between staging and production version of this app. This seems to work despite the documentation (Customize app URLs | Retool Docs) saying it is not supported. We really need this - is there an update so that the _environment URL parameter is reliable for our use case?

Many thanks for your reply in advance!