In general, for real-time jamming while socially distanced, I’ve been using JackTrip, which allows low-latency networked audio. Since JackTrip is audio-only, I usually keep a Skype/Zoom call running as well. Typically, I route my saxophone/guitar through a sound card, through Ableton, and then into JackTrip. I imagine using VCV Rack in place of Ableton wouldn’t be a problem. I was planning to run some tests with JackTrip and Rack a couple months back, but never found the time.
JackTrip is not very user friendly, and the low-latency that it allows may not be as relevant for Rack jams as it is for the improvised music I typically use it for, but I figured I’d mention that it exists.