There are some strategies that you need to follow, by which you can minimize the downtime, and there are some
cloud dr solution that you can follow to manage the downtime effectively, so that you will never face any kind of problem related to downtime. A carefully planned and executed migration should not result in downtime. Or as I know Industry best practices normally call for individual applications/workloads to be migrated one at a time rather than attempting a massive “move everything” approach. This greatly reduces the risk of unexpected downtime or prolonged migration windows.