Our team is always working on new and exciting features for your users. One of these features is supporting the Photos App Extension. We want to make sure that Mextures works in a way that creates the same experience of editing within the app itself. We also want to make sure we can please a large number of our users by implementing the best type of workflow moving forward.
We don't have a specific time table of when this will be available, but we are aware of it and are working on new features for upcoming releases.