Note that the requirement for TAP is not "convert / upgrade all of your production environment to pre-released version" but we expect our TAP participants to run in production, yes. There might be several "rings" of release so for example we might provide a very early version and suggest "lab only" and then provide a later build and say, "production ready".
But the point is to get "real world" exposure to new code / builds and this is simply not possible in lab / dev environments.
If your organization does run a sizable staging / dev environment with real-life (production) workload, then it might make sense. You can apply and we can evaluate the application. But usually staging / dev environments do not provide things like substantial volume of email, number of clients connecting etc. to really see how new changes impact production environments, but yours might be different...