As an experienced Systems Administrator, I have successfully upgraded numerous servers from CentOS 7 to CentOS Stream 9, and I can provide you the necessary instructions to safely migrate your server while keeping your WHM and cPanel intact. My proficiency in Linux systems administration will prove valuable for this task since I'm well-versed not only in the migration process but also in analyzing potential roadblocks that may arise.
In my decade of work experience, I've been extensively involved in tasks similar to yours, from system repairs and troubleshooting to large-scale network infrastructure revamps. I have also worked with different virtualization technologies such as VMware ESXi and Microsoft HyperV, making me comfortable working at a core level with different platforms; thereby, making this migration a run-of-the-mill task for me.
Moreover, my dedication towards following best practices and using industry-standard tools can guarantee a smooth transition for your servers without compromising any data or functionalities. Although I understand you're unable to provide SSH access, I assure you my guidance will be comprehensive enough to assist you throughout the process. Let's get started on enhancing your server performance by migrating effectively!