I've a similar local / S3 (compat) strategy but use Kopia. I currently only backup remotely to B2 (risk taker!), but could easily and cheaply add redundancy in here .. e.g S3 / R2 / random hosting. It's very cheap ~US$1. UI and default strategies are perfect for what's required. Completely automatic unless I need to browse some files in which case I just open the Kopia UI. I haven't used it, but understand Kopia also supports rsync.

Edit: previous comment on same (not a shill, I swear!): https://news.ycombinator.com/item?id=34152369