Or it tells you how much the hardware costs without the manufacturer offsetting the price with the level of data collection and ads they can sell from it?

Or, more realistically, Motorola doesn't move a ton of volume compared to Google, Samsung, or Apple so i imagine they aren't getting amazing bulk pricing on high end parts for this

And how do you finance the high and long lasting firmware maintenance required by Graphene OS, to stay secure?

This first step in the collaboration is not about long lasting firmware maintenance, it's about getting device manufacturer and software developer to talk with each other at all.

Financing security stuff is easy, you cut parts and features until simple and secure parts remain, then you don't update the hardware and do long term quality control, bug fixing and pen tests.

Plus mass production.

The way you DONT do it, is price yourself out of all demographics that care about it being a different OS. "High-end don't care" is covered by Apple.