I use borg the same way you describe. Part of my nixos config builds a systemd unit that starts a backup on various directories on my machine at midnight every day. I have 2 repos: one to store locally and on a cloud backup provider (borgbase) and another thats just stored locally. That is, another computer in my house. That local only is for all my home media. I havent yet put the large dataset of photos and videos on the cloud or offsite.
IMO I think most financial institutions can see or acquire a lot of transactional data, so I just pick one bank (who already knows everything I spend) have a credit card with them, and use it. My bank also allows making virtual cards, so I opt for it over privacy.com.