Put your sensitive data on a microSD card and put the card in your mouth while in the checkpoint, the detector won’t be sensitive enough to pick it up (it doesn’t detect fillings and they are around the same size).
Veracrypt is source-available, but proprietary. A better solution would be LUKS-encrypted partitions. For single files, gpg-based encryption should work as well.
And having source available, and most important can be compiled from those sources, means can be scrutinized for vulnerabilities by security experts, yes? That sounds good enough for me.
If you get in trouble, just swallow.