syslog-ng 3.23 is available in EPEL 8 ( https://fedoraproject.org/wiki/EPEL ). It is missing the C-based Kafka driver (librdkafka in RHEL is too old) and the Java-based destination drivers (Kafka, Elastic, HDFS) due to missing dependencies in RHEL/EPEL.
highly experimental syslog-ng package missing most of the features needing extra dependencies. Core features, Elasticsearch (HTTP) destination are available in the package. You need to first enable the EPEL 8 repository and then add: https://copr.fedorainfracloud.org/coprs/czanik/syslog-ng324el8/
Today I successfully added RHEL 8 support to my git snapshot repository: https://copr.fedorainfracloud.org/coprs/czanik/syslog-ng-githead/ Some dependencies, like recent version of Kafka are available from this repository, the rest from EPEL. As far as I am aware, all OSE features are now supported, except for tcp-wrapper, which was removed from Fedora & RHEL 8. This repository is regularly updated from git.
Once syslog-ng 3.25 is available, the upcoming syslog-ng325 repo will already support RHEL 8 / CentOS 8 and soon after my syslog-ng-stable repo will also receive RHEL 8 support.

As usual, any feedback is very welcome and will be handled with best effort. I'd especially welcome feedback on my syslog-ng-githead repo -- even if that's not intended for production environments -- as that's where I prepare for the next syslog-ng release.

Bye,