Found this https://community.playfab.com/questions/49435/multiple-networks-at-the-same-time.html when looking to see what the Party Unity SDK supported. Reading through https://learn.microsoft.com/en-us/gaming/playfab/features/multiplayer/networking/party-features#flexible-topology-design-possibilities really paints the picture of being able to be connected to multiple networks at the same time.
For my part, and the game in the making; assembling a squad, with a separate network to use voice and taking advantage of all the callbacks that Party provides, complemented with connecting to another network, which handles the game logic, would have been awesome.
