In the same boat as the other poster, its been like 10 years.
I used GNS3 and Cisco VIRL way back in the day.
Depending on your use case, you can pretty far with just docker and some Linux packages. I’ve done GRE, BGP, OSPF, ISIS, Open vSwitch. That’s Linux networking though. If you’re trying to prep for a specific vendor’s cert, it might not meet your needs.
Does look like someone had success running virtual devices in docker that might be of interest: https://github.com/vrnetlab/vrnetlab
Same. Have it baked into my neovim setup.