Recommend you follow the 321 backup strategy. Adopted to modern times I would say it is broadly:

• Have your data in more than 1 place
• Use more than one provider
• One of your types of backups should be physical media like an external hard drive.

From what you described if apple was to wipe your data[1] you would be completely out of luck… for example if something deletes data in your Mac and then that deletion gets synced… For the most part syncing data is not a backup.

Lastly, recommend you try to put all your critical data in one folder, or identify folders with critical data and prioritize backup of those first while you figure out the rest.

[1] Not only can a deletion “sync” from your mac, but there can be any number of issues… like a bad update to a file. There is also the possibility, no matter how small, that apple could wipe your data. Over time you always see news of “company X deleted entire set of data for user/company Y”.

https://www.lunanode.com/ Only one data center in Canada, but affordable and have used them for years without issues. VMs starting at $3.5/month

You still need some means of outside backup. Figure what you have covers majority of scenarios, so now we are getting into the highly unlikely, but highly impact full like “my house burned down and now I have no data”. Something like B2 (or some other block storage with comparable pricing) is worth exploring.

You also need to consider your usage pattern like whether you may need to retrieve data (some providers charge for bandwith in / out). I would suspect most of the time between your ZFS snapshots and your disk you are covered.

Also, recommend to not leave the disk plugged in at all times for the scenario I mentioned: Your machine is compromised and the attacker encrypts data to ask for ransom; very low probability (I suspect those are mostly against companies), but really doesn’t hurt to prevent against it.

yes the ZFS snapshots are in the same disk, but the most common scenario when you need backups is to get a handful of files in which case the ZFS snapshots are super convenient and they use very little space. I use restic + (B2 | sftp) and zfs snapshots. I may literally go years without needing to restore from restic because most of the time I can get what I need from the zfs snapshots.

You did not mention if you are using a single disk or more. If you can afford it and the machine allows it, doing mirroring or RAID-Z1 (equivalent of RAID 5) is a good option

Suggest:

• Frequent ZFS snashots. There are scripts to make this easier like zfsSnap
• Two external backups which you rotate weekly [1]
• Instead of borg backup of ZFS pools if you have another machine you could sync the volumes to another machine or even use rsync to another machine of the data [2]

You did not mention where the target of the borg backup is, but you want an external service. I believe there is a service that works wells with borg backup, but have not used it.

Notes [1] Spinning disks are affordable. I suggest at least 2 because if you only have one and your machine was compromised, think disk encrypting malware, you disk may be encrypted too. Also, if the disk dies there goes your external drive backup

[2] If you have another machine with enough space to host a copy that is a good option. Also, there are services that offer backup/disk VMs. They have very slow CPUs and affordable disk. Those may be work checking

1 of which is off-site (in a safety deposit box, for example)

A potential compromise these days may be a block storage service. Safety deposit box is good, but because of it’s inconvenience people are very likely to do it seldom, which defeats the purpose.