I have oracle instantclient 19.3 installed and can see that OCI8 is loaded in PHP from a terminal by running php -m. I also added LD_LIBRARY_PATH and ORACLE_HOME and environment variables to /etc/php-fpm.d/www.conf. They show up correctly in the environment section in phpinfo.
However, oci8 still does not show loading from apache.
Any suggestions on what else I can try to get this to work?
Miracle of miracles. Oracle has a specific instaclient for Linux 8. You can download it here. https://www.oracle.com/cis/database/technologies/instant-client/linux-x86-64-downloads.html
Installing that driver took care of the problem. Wahoo ;)