Hi!
Thanks for your comments! I am unsure regarding your hunch that the oVirt Repo is to
blame, as from inside the engine after the botched deployment, absolutely nothing outside
of the engine and its host is reachable via IPv4/v6, and a manual "dnf update"
also produces a failure that the AppStream metadata can't be fetched. Therefore I
still believe it's a bug with he temporary networking/dns setup used when deploying
the hosted engine.
I have sufficient space on the host, even after the engine was (half-)deployed there is
still 80% free space available.
The only connection problems I had with the oVirt repo were that it is not IPv6 ready.