We have used SkyKick several times as a migration tool from on-premises hosted email to Office 365. Microsoft does not make it easy for these migrations and a high level of expertise is required. That's where SkyKick comes in to simplify the whole process. We also use their Cloud Backup service to backup Microsoft 365 data. This addresses the risk of having one single copy of your data when moving it to [the] cloud, as well as relying on a cloud provider to look after it.