reading this was so nice.
I'm sad to learn Neil left, I hope the project won't suffer.
About location sharing: have you considered about the privacy issue of downloading tiles? This might disclose your location. I know there was a messenger that planned using #peermaps peermaps.org/ to mitigate that.
For the funding we are doing our part (with @copiepublique) but have you considered a progress bar? If crowdfunding platform use this pattern, it may work (gamification?)