I have a number of Citrix on Prem servers that are accessible through Citrix cloud and the gateway. However, the VDAs are still pointing to the local on prem broker, data collector ect. Is it trivial just to point the on prem VDAs to my cloud connectors and register those with the cloud so that the only thing that is on prem is the vda itself? (That way I can get rid of all other non VDA server roles on prem)

Correct. You just need to point them to the Cloud Connector and the Machinecatalog has to be defined in CTX Cloud.

And i can just go into the registry of the vda to point that server to the cloud connector? Or uninstall and reinstall correct? Anyone recall that registry setting

It is the ListOfDDCs reg key. just a sec

This correct? , https://docs.citrix.com/en-us/citrix-virtual-apps-desktops/manage-deployment/vda-registration.html

Correct