NDI Tools
NDI Tools are a suite of tools made by Newtek for sharing video and audio across networks using the NDI protocol. While it is usually geared towards running on local networks as of version 5 it is possible to share video sources across the internet using NDI Bridge. NDI has direct compatibility with most modern video programs and has plugins for the Adobe Creative Cloud.
While NDI can be fairly CPU heavy to encode and decode, it can open up a whole host of possibilities for sharing video across various machines. There are apps available to share smartphone cameras and screens as NDI sources and the tools package contains the NDI webcam utility which creates a virtual webcam (for zoom, etc) using any NDI feed on the network.
The full set of tools is Windows only but the MacOS tools still offer a lot of functionality.
COST:
NDI Tools are free
Some apps are paid
Specific hardware is also available