Personally, I use encrypted sparse disk images. (You can make them with Disk Utility.) It makes a disk image using many small files in a folder. Might leak some information related about size or number of the contents, but the contents and metadata of the filesystem are encrypted.

This method can result in corruption of the disk image if you’re not careful.

Edit: This is probably the most seamless way to handle encryption. It’s built in to the OS and you can save the password in Keychain if you like. Used it with Dropbox for years. Just make sure to unmount and let it sync before opening the disk on another system.

Restic is one option https://restic.net/

Personally I split everything into equally sized tar.gz files, encrypt everything with gpg and upload it using rclone. It should be easily doable and scriptable in any Unix-like machine. It's not the fastest way of doing this, and very inconvenient if you need to access the data often. I only use this for off-site archiving that I will never use unless something catastrophic happens.

There are tools that will provide a virtual drive backed by files that are encrypted on disk. I use Cryptomator [1], which is cross-platform and is designed with cloud syncing in mind, but on mac you can just use Disk Utility to create an encrypted DMG.

[1]: https://cryptomator.org/

I’ve been trying duplicati recently and it seems fairly simple and is cross platform with a GUI

I use rclone crypt for that (https://rclone.org/crypt/).