I cannot comment on the other issues. For using the smartphone as an webcam ( and microphone) you can use Droidcam. See this forum post for more details.
Installing headers ( MUST! for droidcam )
List out the kernels in your Manjaro system
$ mhwd-kernel -li
Currently running: 5.9.10-1-MANJARO (linux59)
The following kernels are installed in your system:
linux54
linux59
Install the headers for your respective kernel via pamac-gtk or with terminal command:
$ pamac install linux54-headers linux59-headers
give your system a reboot.
Installing Droidcam - Manjaro
Build droicam with the command:
$ pamac build droidcam
this command bui…