EL9 support is being added, according to the devs. But there are still issues, so be patient with Rocky 9 or AlmaLinux 9.
The best OS for CWP is actually still CentOS 7.9, but that is a dead end road, so I wouldn't recommend starting in with that release EOL in ~1 yr. I think you're best off with EL8 release for a new install like Rocky 8 or AlmaLinux 8. With those you have migration scripts, so you should be able to "crossgrade" between distributions if another becomes the clear favorite. My personal plan is to hold out on CentOS 7.9 until next spring and then migrate to AlmaLinux 9. CWP should be fully ready to go by then!