1. Clone the on-prem production instance and name it a staging instance.
2. Run the rules only upgrade on executing the upgrade.sh commands. Then create the RAP with the applications and required data instances that you want to move and import into the cloud Pega instance. The advantage of RAP is that it is intelligent enough to create the tables according to the destination Database means it is independent of the DB that we are using.
3. Run the data-only upgrade. This would upgrade the data schema and move that data schema to the cloud environment.
@abdulq95 Above and all, as we are moving from on prem to Cloud, we need to take care of the Production transactional data and downtime. We need to copy the data and put the system on hold to make sure there is no further changes to the data.