This is great, big projects feel like you’re Wil E. Coyote running off a cliff, a whole bunch of running in place until you fall.
So Agile doesn’t scale, and that’s a good thing. It’s not supposed to scale. It’s supposed to help us realise that we need to scale down. Split stuff into smaller parts. Build a prototype. Deliver frequently. Get feedback from real users quickly. You know the drill.