I just went on docker hub. I search for Redhat Enterprise Linux and RHEL.
I get ubuntu with 1B+ downloads. I get oraclinux, amazonlinux (?!?), alpine, debian and more. If they are releasing docker base images they are doing an absolutely terrible job getting them distributed. I'm honestly kind of shocked to see amazon here, are people developing against Amazon outside of just spinning up hosts on EC2 etc? Amazing. I might do that myself.
Edit: Amazon Linux looks fedora based for 2022 forward, but with 5 years of support - that's not a bad combo if they can deliver. I'm going to try it for my next project. Their Amazon Linux support has been poor in the past at times.