Has anyone got retained and got the chance to move onsite.

Talks will start only if your manager wants you. But, it does not guarantee that you will get retained even if your manager wants you. This has to get approved in other levels as well. You can get onsite if your manager is fine with it.

Onsite - They can give oral confirmation.

Retaining associates are solely dependent on consensus of reporting manager and hrbp. In my project 11 left and nobody were given second chance to talk. It seems these people are showing doors with grace unfortunately.

But why do you want to get retained? If you have good offers then leave. If you don't have offers you shouldn't have resigned.