How do you fix an activation flow when the core value requires heavy initial setup?

Our product delivers massive value once fully configured but getting there requires connected integrations, team permissions, and data importing.

We tried shortening the onboarding steps, but skipping setup just led to empty states and fast drop-offs. Leaving the full setup in place means a large percentage of signups abandon before finishing.

For products with complex setup requirements: how do you deliver an "aha moment" early enough to keep users engaged through a heavy onboarding process?