Great, thanks for the response, and what you mentioned the messaging could revolve around sounds great to me.
Do you plan to have any super small-scale user studies where you can very closely see how the whole thing goes before running any larger-scale onboarding programs? Like, connecting to even just 3-4-5 people that you know and seeing which messaging points they respond to with excitement, and then looking at their device or doing a screenshare to see exactly what happens on their journey? Doing such in-depth user studies and documenting the findings (typically as video recordings that can be analyzed later) can be extremely informative before running any larger campaigns where you are zoomed out and see only numbers without all the real-world nuance and intricacies which answer why the numbers look as they do.
The book The Lean Startup describes this, and the book Lean Analytics goes into crafting actionable and reliable metrics (such as using ratios instead of absolute numbers).