I do not see a build for Cubox i2/i4 and Hummingboard - will there be Leia build for imx6 platform?
No. iMX6 support was broken for the first 6+ months of Kodi Leia development and since nobody stepped forwards to act as maintainer the dead code was eventually removed, so it's not possible to make an image. It should be possible to reinstate support using modern kernels in the future, but some technical (driver) things need to be resolved first to make that possible. It's something we're continuing to track.