The current apporach to build FDIs is quite limited:
FDI currently builds only against EL 8 and building in a container will NOT work (docker/podman). The building host MUST be EL 8, other versions or Red Hat compatible systems (e.g Fedora) WILL fail to build.
But what’s about building FDIs based on Ubuntu on any build host?
This is were KIWI comes in. KIWI is an appliance builder supporting the build of live systems among others.
Find the FDI KIWI image descriptions here (currently Ubuntu 20.04 + CentOS8):
Depending on the circumstances, this could be an alternative workaround for the SecureBoot issue (Add SecureBoot support for arbitrary distributions).
There are more OS supported by KIWI. Find example image descriptions here: GitHub - OSInside/kiwi-descriptions: Provides a collection of kiwi image descriptions
There are some issues in KIWI at the moment you might need to consider if you want to use built images on UEFI/SecureBoot enabled hosts: