Great example of try first, signup later that I coincidentally just discovered is Litmus' email rendering preview system - https://litmus.com/email-testing

They go quite far with it, which was really nice for my specific use case, allowing me to share the results with my team before proceeding with registration.

Now it begs the question whether or not I'll come back later to signup for the service, but regardless they've left a fantastic impression on me as a potential future user.