uberXMHF Raspberry PI 3 Version

Is uberXMHF available only in Raspbian Jessie Lite with Linux Kernel 4.4.y version as described in https://uberxmhf.org/docs/rpi3-cortex_a53-armv8_32/supported-os.html or it can also be implemented in the current version 4.9.y ?

Raspbian Jessie Lite distribution with Linux Kernel 4.4.y 32-bits is the currently supported version. However, in principle, you should be able to bootstrap a more recent 32-bit kernel version (e.g., 4.9.y).
Have you tried building a 32-bit 4.9.y kernel on the Jessie Lite?

We have only try it on the current version 4.19.y since it is the version that we have to use for this project.

The first step would be to build a 32-bit 4.19.y series kernel on the 4.4.y 32-bit kernel/Raspbian Jessie Lite Distro.

Most of step-5 in the uberXMHF-rpi3 build documentation (https://uberxmhf.org/docs/rpi3-cortex_a53-armv8_32/build.html) should apply, but replace 4.4.y with 4.19.y…Let us know how that build goes…