I spent a bit of time trying to mount some existing LUKS2 devices on
boot in a Guix system. They worked to open and mount manually in a
booted system, but not on boot with luks-device-mapping. Eventually
worked out LUKS2 is not supported by the code that inspects the
superblock directly for the (LUKS1) UUID.

A mention LUKS2 is not supported in the docs might be nice.

Cheers,

Dave Trudgian