The  ODroid XU4 series are a family of credit card-sized ARM based single board computer (SBC). FIXME - testing needed: Fedora supports the the XU4, and closely related variant HC1 in Fedora 27 without any requirement of third party kernels or scripts to adjust official images. This documentation describes how to get started, and includes a Frequently Asked Questions (FAQ) about what is supported and what isn't.
Some of the Fedora community have barely restrained  hostility to Exynos devices
- From my point of view the Exynos devices are "best effort", I personally don't have any devices to test, the Odroid manufacturers generally don't give a shit about anything upstream and no one in the community has stepped up to be the maintainer of the (Exynos) devices
This of course also represents an opportunity for developers to step up, and to dispel that attitude with documentation and stabilization work, such that this Caveat might be removed