I started working on encryption. I'm adding support for encrypted save folders using the fscrypt API and my plan is to reimplement encrypted save files using the same technique (instead of using LUKS). Currently, save folders don't support encryption, fscrypt can be more efficient than LUKS, and fscrypt allows encryption of specific directories rather than the entire file system.
The fscrypt userspace tool is big (several MBs) because it's written in Go (and I love Go, I use it professionally all the time), so I wrote a tiny replacement in 136 lines of C. It's not equivalent, only locks a list of directories using a key derived from a given password or unlocks all directories locked with the same key, but it's adequate and tiny.
My plan is to enhance Bootflash even further. Its yad-based reimplementation in my woof-CE fork already offers the user choice between PUMODE 5, 12 and 13, and uses an improved partition layout with less wasted space, among other improvements and simplifications. I want to move save file/folder choice from first shutdown to Bootflash (if the user selects PUPMODE 12 or 13), and give the user 6 options:
1. Save folder
2. Encrypted save folder
3. Save folder with encrypted home directory (default?)
4. Save file
5. Encrypted save file
6. Save file with encrypted home directory
Encrypting only the home directory (/root and /home/spot) sounds to me like good balance between privacy and performance, especially with PUMODE 13, because decryption happens only something reads an encrypted file or when a file is "copied up" to the RAM layer, and encryption happens only during saving.