The soul of a machine
This project is maintained by wbreeze
MacOS will nicely encrypt any file system. In order to do so,
If the “disk” isn’t formatted with a file system that supports encryption, you can use the Disk Utility to reformat it as MacOS Extended (Journaled, Encrypted)
Remember to save the passphrase in your password safe. MacOS will offer to remember the passphrase in its keychain as well. That is great!