I often run two GoPro Hero 12 cameras and one GoPro 360 all from my phone in flight. I use an Android phone too... so I can confirm the GoPro app works with Apple or Android. I change my camera locations around depending on the mission however I often have two mounted externally and one internally.
Prior to cranking up I turn the cameras on, then place them into a standby mode from my phone until I'm ready for them to start recording. When you're ready its easy to turn them on via the App, then push record. Job done. You can cycle them on and off as much as you like until the battery goes flat, then you have to wait until you land to swap out the batteries. Typically they'll last an hour or so when recording. I've not tried wing-walking to replace the batteries in flight.
Here's a link to the video I uploaded earlier this week, using two cameras placed on the wingtip and controlled in this way.
There are other videos on the channel too if you're interested. Its a lot of fun. Having one camera inside allows you to capture audio and adds to the perspective.
With the GoPro QWIK App you can change some of the camera settings from the cockpit in flight and while recording you can see the preview. I used to use the GoPro remote control when I ran a single Hero 4 camera however I found that when the camera was mounted under the wing it could be a little unrelieable. Maybe there was too much aluminium in the way, but turning the camer on an off was sometimes difficult. I've not had these issues with the Hero 12 and the QWIK app.