What is the secret to product?
To put it quite simply (and reductively)...
1. Build something awesome that solves a real problem
2. Put it in front of the right people and get them to the value as quickly as possible.
The secret to product onboarding
With this in mind, be careful about one-time "onboarding" experiences that attempt to do too much work compensating for weaknesses in the core product.
Instead, consider how you can make the core product more easy-to-use, self-explanatory, delightful, and adaptable. And then get users in there as fast as possible!