I’m not a mac user, but if you’re manually encrypting your backups before storing them (and you have a good way to remember/store the keys to decrypt it), that’s a solid offsite backup.
Along with this, you should probably have an onsite backup as well. Choose your storage medium well.
USB drives: Avoid. Not super leakproof.
M-disc: for a single write, but they last 30 years. Good for super long term stuff
SD cards: A single write should last a few years, so not a bad backup method. Limited write cycles, so don’t reuse it too much.
HDD: if you’ll be rewriting/accessing this backup super often. In this case, use another medium as well to make longer term backups.