The first thing I noticed: I hadn’t enough space to record properly, so time for some rearrangement:
One big improvement for videos is the sound. So I switched from built-in mic to a lav mic for my voice.
For the guitar sound it’s not enough: we need a direct mic on the amplifier.
I use one of my old Shure SM57 on a mic stand
To improve the lighting I use a Falcon Eyes RX-8TD
The Camera Setup
The upgrade from iPhone 6 to iPhone 11 Pro was a big step. Nevertheless you need good gear to fixate it: