The official GoPro article on the GoPro website says that it is not possible to control multiple GoPro cameras with the Quik app at the same time. But there is a solution for this problem.
Since version 1.3.2 the mobile (Android, iOS) version of the Camera Tools app supports the following keyboard shortcuts which can be used with a Bluetooth keyboard:
This article describes tools for replacing the GoPro Quik and GoPro Studio software. Both GoPro apps have been discontinued on desktop platforms and do not (properly) work anymore with the latest GoPro models.
Fortunately great alternative apps exist which allow you to use your GoPro from a Mac, desktop PC, and Raspberry Pi. Most tools are also available for Android and iOS.
GoPro Hero 7 Black Edition, 8, 9, 10, and Max cameras support live streaming to YouTube, Meta, Twitch, OBS Studio, Mona, and other RTMP servers with the Live Streamer app. This article describes common problems and fixes which can happen during live streaming with GoPro cameras.
Sometimes the GoPro camera is located at difficult to reach positions so that it cannot be controlled directly. The classical way for controlling the camera in such situations is through an app (e.g. Camera Tools for iOS/Android). This again has the disadvantage that we have to eventually pull out the smartphone, unlock it, and start the app.
This article describes how to setup a RTMP streaming server on Apple macOS. The streaming server can then be used to stream from multiple sources, such as multiple GoPro Hero cameras.
This article describes how to setup a RTMP streaming server on Windows. The streaming server can then be used to stream from multiple sources, such as multiple GoPro Hero cameras.