I have run SELinux on Fedora without too many issues. Of course, Fedora being rather closely related to RHEL that shouldn't be too surprising.
Yes, it's not that simple, and there are some customization done. But Fedora is the playground for the next RHEL. I woudn't consider Fedora "an alternative" according to what the top-poster was describing.
I've heard that a lot but I don't think this is an adequate comparison (yes even with the disclaimer in the next paragraph). First of all because of the relative stability of Fedora, I've been updating my OS since Fedora 29 and every major upgrade is mostly boring. Second, there are some decisions made in Fedora that wouldn't make sense if it was merely a test bed, removing the whole Java stack comes to mind, or more recently the libreoffice debacle.