First, thanks for your time in creating and managing armbian :)
It will be great if cryptsetup work "out of the box" (without rebuilding your own kernel) (at least in devel ;)).
At the present time, I can't mount any encrypted partition because some options are missing in the kernel.
I think the kernel option "CONFIG_CRYPTO_USER_API_SKCIPHER" is needed.
The module dm_mod.ko is also needed but I can't find which option(s) creates it (it's the device mapper module).
It will be also great if we can try the CESA code since the option seems here (CONFIG_CRYPTO_DEV_MARVELL_CESA) , so we can test it :)
I paste below the results of my simple tests.