Cyberduck is a libre FTP, SFTP, WebDAV, Amazon S3, Backblaze B2, Microsoft Azure & OneDrive and OpenStack Swift file transfer client for Mac and Windows.

GUI software to access any and all of the above (and more) protocols/services. Includes e.g. access to both Nextcloud and Dropbox storage and your S3 buckets on top.

Runs in its own GUI so too cumbersome for me, but also is the foundation for the paid 'Mountainduck' software (for Win and Mac) which incorporates everything into the explorer GUI and thus runs as invisibly as on Linux mounts. Pretty clever!