How would you go about answering this question for them?
What research approach would you adopt in order to answer their business question?
I would propose a two-stage research approach to explore the topic, with the second stage as optional
Post-Mortem: how are the customers currently using the journey: What is the data available about if and when customers currently drop off the journey? Are most of them non-starters or are the steps in the journey that cause the drop-off? Could it be that because it is a blended journey there are additional friction points that are not product-specific? Which parts of the journey perform well? Customer expectations: what are customer needs that have to be addressed for them to complete their customer journeys What are customer requirements for this journey? Research Questions and Business Objectives
How will knowing an answer help answering the business question and support business objectives?