HDMI ubuntu 20.04 xylinx zcu104

Description

LVGL through the HDMI port on an aarch64 board running Linux from framebuffer

What MCU/Processor/Board and compiler are you using?

Xylinx zcu104 dev kit (aarch64) running stripped-down Ubuntu 20.04 or newer.
g+±13

What do you want to achieve?

A running GUI on a 7inch display using the HDMI port without a desktop environment using framebuffer

What have you tried so far?

I have not tried anything yet: I would like to assess the difficultites, such as
a) is a custom kernel needed
b) bootloader args
and whatever advice might be given in response to this.

Thanks in advance