If RHEL binary compatibility is not strictly required and if using in-tree kernel modules only (i.e.: no out-of-tree kmods are required), CentOS Stream should remain a viable option.
Otherwise you can use one of the new RHEL clones, such as AlmaLinux, RockyLinux or even Oracle Unbreakable Linux (in this case, be sure to select the RHEL-compatible kernel rather than its own customized kernel).
Personal note: I am using RockyLinux with no issues at all (I migrated from a CentOS 8 box with the
migrate2rocky script) but, as always, your mileage may vary.
Finally, if you are sure to need fewer than 16 RHEL instances, you can use plain simple Red Hat Enterprise Linux from Red Hat's free tier (with no support, obviously).
EDIT: as wisely suggested in other answers, migrating to a different distributions as Debian, Ubuntu, etc. is a very reasonable approach. I did the same (rebuilding with latest Ubuntu LTS) in environments where RHEL compatibility was not required. Debian and Ubuntu officially support in-place upgrade paths while most RHEL clones only have unofficial support - RHEL itself and Oracle Unbreakable Linux being the exceptions, with fully supported
leapp upgrades - but things are changing now.