There's also Fedora. Part of what you're doing when you register with your no-cost developer license is tie into our repos of tested, patched, and supported (for paying customers) RPMs and containers. And you get that because you gave us your email and possibly/probably signed up for some newsletters that you can opt out of later.
There's no-cost developer licenses as well that you can use with subscription manager. And, of course, there's also CentOS for free-as-in-beer.