Build a Flow that is 5 steps where steps 1-4 are all events, but step 5 is filtered to actions that match purchase. Name it and save it, then in Explore view, using a Sankey visualization, count the number of instances of your flow and split it by Action. Run it from 7 days ago to now.
Open the Flow app. Build a flow that includes 5 steps (add steps by pressing the + step button). Steps 1, 2, 3, and 4 can be left alone, where step 1 starts flow on all events, step 2 transitions from step 1 on all events, step 3 transitions from step 2 on all events, step 3 transitions from step 2 on all events, and step 4 transitions from step 3 on all events. Step 5 should transition from step 4 and be filtered to Action that matches purchase. Once that is completed, give the flow a title, for example, "My Purchase Flow." Next, open the Explore builder and use the Sankey visualization. In measure 1, in the "event" dropdown select the flow you built and named in the first step. The measure should now read count number of instances of "My Purchase Flow" or whatever you named it. Last, add a split by of Action and make sure to visualize as a Sankey view after you press go. It can run from 7 days ago to now.
Flows are a powerful way to set up sequences of events that users perform inside of a session. Note, these are not sequential actions inside a session, unless you leave the steps to filter to all events. Meaning if you filter step 1 to action that matches home page view, and step 2 is filtered to purchase, the user does not have to perform a home page view event then immediately go on to purchase. The flow is only looking to see if a user did a home page view and then at some point in the same session perform a purchase before that session ends. Session rules are set in the Global Rules section of the flow builder.
Note: The numbers and result does not need to be an exact match as the data changes over time. The query construction is what is most important. See images below.
*Click to enlarge*