https://bugzilla.redhat.com/show_bug.cgi?id=2160996
--- Comment #7 from Ben Beasley code@musicinmybrain.net --- Are you sure this package needs to be ExclusiveArch: x86_64?
Upstream documentation (https://github.com/google/draco/blob/master/BUILDING.md) suggests that at least i686 and aarch64 should be supported, and after removing the ExclusiveArch line I was able to do a successful scratch build for all current Fedora primary architectures.
It would be good to get the tests running so that we can be sure everything is really working properly on all of the architectures.