Using Transit Gateway, organizations can enable connectivity between different VPCs across different AWS accounts and on-premises via AWS Direct Connect or VPN.

Alkira’s integration with AWS Transit Gateway Connect provides a complete cloud services and cloud management portfolio that gives enterprise customers fast, flexible access to the cloud ...

Since 2015, S3 has come equipped with a VPC endpoint but this has not allowed AWS users to access S3 from on-premise solutions over secure connections like AWS Direct Connect or AWS VPN.