I have been using Duplicati uploading directly to Deep Glacier. I have multiple local copies of the data + local backups to a RAID array, so the backup is basically an absolute emergency break. The downside is that it’s not possible to verify the uploads immediately (because the files cannot be retrieved), the upside is that my backup is 225GB and it costs a few dollars per year. Uploading to regular S3 and quickly cycling to Deep Glacier would be more expensive, though it would guard against the marginal risk of a corrupt upload.