Something like Rclone and a cron job, or else s3 mounted via FUSE, could possibly bridge that. Of course then you have to worry about reliability of the bridge...
Mounting S3 with Fuse is not stable or performant enough at scale for backup storage
https://github.com/Barre/ZeroFS Should do a great job at this.
There’s support via Barman cloud - we use it for azure at work but s3 and others are supported iirc