Each AI cloud provider can offer connector banks to offer federated or customer VPC sourced access to S3/DB/DW.

Ref: public and private access of services and apps split-horizon dns, high availability
Also see this image for AWS DirectConnect view of this solution/use-case
For more details see - Example Use case C: Scenario 1 in
Ref: https://docs.google.com/document/d/1hPrg2bdFD9GC5q1u9hROZv0Y4aG4Nxsf3cuhIQDwvEU/edit?tab=t.0