Rodrigo Gomez-Palacio

Free and easy, Firebase is the default option.

Best way to easily set up paid subscriptions.

I'm a OneSignal alumni :) and it's a great product.

Going to be hard to pull off. I'm surprised Sam Altman doesn't have the foresight to see that in a world where no one trusts institutions no one will willingly pay to scan their eyeballs without an obvious value proposition. Most people don't even understand Bitcoin yet