Support for the A6 v3 is being discussed here:
The C6U and C6 v3 appear to be at least very similar, so supporting the v3.20 probably won't be that hard.
Edit: comparing the C6 v3.20's firmware to that of the A6 v3, the kernel and file system appear to be identical. The flash layout is also identical, so maybe you can even already try booting an A6v3 initramfs if you have serial access.