[root@meimei ~]# dnf whatprovides netdiscover Last metadata expiration check: 1:30:03 ago on Mon 02 Sep 2019 07:03:55 PM CST. Error: No Matches found
Can we assume you get this from a 3rd party repo?
To be honest, I have been using it in Kali, I saw there is a RHEL spec file. This will be a good weekend project to have it available in copr, hopefully in Fedora official repos.