Sktime contains a handful of standard tools and models used for time series analysis and machine learning.

Prophet contains one specific model developed by Facebook, which you will not find in Sktime.

You won't ever find something like Prophet in Sktime because it's a "higher level" model than anything in Sktime. The cleverness of Prophet is based largely on its automatic feature engineering, with a linear regression model underneath. Whereas a library like Sktime focuses on implementing specific models like ARIMA, and letting you do your own feature engineering.

sktime is a toolbox with the goal to support multiple models and composition techniques, Prophet is a particular model. We're working on interfacing it so that you can call it using our API.