Although Mixpanel’s Funnels report allows you to measure time to convert between specific steps (e.g., A → B), each funnel step is defined by a single event, not a group of alternative events. The documentation describes measuring time to convert between steps, but does not mention configuring a step as "any of these events" (B, C, or D) out of the box.
An important metric that many product teams like to look at is "Time to first value". The point of this metric is to see the average time it takes for a new user to get meaningful value from the product. In our case, the "value" can be any of several tracked events. This is my personal experience with this limitation, but you can see how this this grouping of steps can be useful in other contexts as well.
