Depends on what exactly it wants to do. You could use S3 static site hosting behind CloudFront with Lambdas for the functions. Not sure if it would scale to that number of users though. My project gets very little traffic.
That could work for a smallish CRUD application I think (just using the function as a service approach to really squeeze efficiency out of the compute time), but yeah the specific numbers aren't quite as important as learning about how to acquire a scalable fraction of the power behind the massively distributed platforms that now dominate the world. This seems like one such approach that some devs have very definitely made working services from, based on a quick search.