It itself is not FOSS, but Network Chuck just had a decent video on setting up ThinLinc for his editing team. I believe it is free for ten or fewer users. There is an admin function that allows you to observe what another user is doing (session shadowing).
https://m.youtube.com/watch?v=qdo5lMR1lX4
In general, for native FOSS, I’m pretty sure you can specify the screen port in VNC, and connect multiple users to the same port, but you’d have to double check the configuration file. Can likely also be done with XRDP.
What is your degree program? Or, what is your career path?
In general, when people say “Cisco” certs, they almost always mean CCNA, which is the associate level Cisco certification, and gives foundational network knowledge that is highly valuable and transferable to other IT and cyber fields.
Cisco CBROPS probably won’t get you in the door at a SOC without other work experience or certifications, unless the place is super aggressive about churning through SOC I analysts.