Creating video tutorials for sighted users

Hello All.
I need to create some tutorials for sighted users, so they must video tutorials not audio only. And here comes the problem. I need an application that can accept video and audio input from an iPhone connected to my Mac and my voice from a mixer also connected via USB. I tried QuickTime, but it is insufficient: it can only accept one audio source, so I can have the video and the audio from the iPhone or the audio from the mixer but I cannot have video from iPhone and audio from iPhone and mixer at the same time. OBS is not accessible under MacOS, so it is not an alternative.
Can anyone offer a suggestion?
Thanks in advance.