In Firebase Analytics, the Funnels page only SHOWS open funnels. To create CLOSED funnels, the EVENTS that the developers create have to enforce this. For example, if the following flows are POSSIBLE:

FLOW 1: Screen A, Screen B, Screen C, Screen D
Flow 2: Screen X, Screen Y, Screen C, Screen D

You could log the following events :

Flow 1 → A, B, C_1, D_1
Flow 2 → X, Y, C_2, D_2

Each set of these creates a closed funnel in Firebase Analytics. You can then create an audience of users who log all events in each Flow.

In Firebase Analytics, the Funnels page only shows open funnels. To create closed funnels, the events that the developers create have to enforce this. For example, if the following flows are possible:

Flow 1: Screen A, Screen B, Screen C, Screen D
Flow 2: Screen X, Screen Y, Screen C, Screen D

You could log the following events :

Flow 1 → A, B, C_1, D_1
Flow 2 → X, Y, C_2, D_2

Each set of these creates a closed funnel in Firebase Analytics. You can then create an audience of users who log all events in each Flow.