My setup is quite similar (2012 Mac Mini, dockerized Hyperion NG in a Photon OS VM on ESXi) minus the fact that my capture hardware is a USB camera instead of a grabber.
I'm using WLED over WiFi with 5M WS2812B strip (130leds) without problems, but if you want to avoid networking you can control WLED via serial over USB.
Can you explain more details of your settup. I want to do something like this, but dockerized in RancherOS VM on TrueNAS. I wonder how to install Hyperion with docker?