Thanks for the tip Jun, it looks like the install docs which refer to redhat 7.3 can also be applied to redhat 8.0. Once I installed the compat libs the installer started working correctly. I haven't quite finished the install, but when I'm done, I'll update the install docs to add a note about installing with redhat 8.
As far as oracle 9, there were some past discussions about using oracle 9 with openacs 4. I think there are still some issues with regards to running oracle 9 with openacs 4. If there are still any issues left, I think we should think about rectifying them for the 4.7 release.