Q: What is an objective of AlmaLinux OS?
A: To be 1:1 binary compatible with RHEL®.
Therefore, AlmaLinux 8 is compatible with RHEL 8.
Logically, AlmaLinux 9 will be compatible with RHEL 9.
You can’t be compatible with RHEL 9 before there is RHEL 9.
How “advanced” RHEL 9 will be compared to RHEL 8? Ask Red Hat.
When will RHEL 9 be released? Ask Red Hat.