I mean Secure Folders. I still have my Pixel. I can't make Secure Folders. On my Samsung I have Secure Folders which creates its own sandbox environment and I also have Work Profile and in that Work Profile I can have Secure Folders too. So really if you want to you can set a passphrase for your main profile, your work profile and the secure folder in your work profile. Three layers. Knox is using verified boot and the latest Snapdragon TPM chips. Along with Apple and Blackberry they are the only devices the NSA approves to hold sensitive but unclassified information.
DSA approved list