To upload the files into an S3 bucket, there is other recommend way is using a desktop tool that will preserve the directory structure and will recover if your network connection is interrupted.
Amazon S3 (Simple Storage Service) is a cloud storage service that allows users to store and retrieve any amount of data, at any time, from anywhere on the web. S3 buckets are a popular storage option for businesses and individuals because they offer scalable, low-cost storage for a wide variety of use cases.
Object Store on SAP BTP
Store and manage the blobs/objects on SAP BTP.
Overview of Object store
Object Store service on SAP BTP lets you store and manage objects, which involves creation, upload, download, and deletion. This service is specific to the IaaS layer such as Azure Blob Storage, Amazon Web Services, and Google Cloud Platform