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Could be problematic if the image is huge.

Anyone have experience with Boxcryptor? Haven't tried it since a few years ago (https://www.boxcryptor.com/en/)

You could use something like gocryptfs that encrypts at the file level

Cryptomator is another cross-platform alternative for file-level encryption: https://cryptomator.org

Also includes first-class support for cloud syncing apps.