This is not a kernel panic that you describe, so you should better change the topic title to something else.
Your bootloader is trying to find the kernel, which is configured to be on a /boot separate partition.
For some reason, probably some miscofiguration, it cannot find the kernel, so the system (Linux/Archlinux/EnOS) cannot start.
You haven’t explained how did you install your system, and what configuration you have selected during installation (mainly regarding system partitions).
Give more info, so you can get a more specific advice.
PS: Since this is not a kernel panic, the article you have tried to follow cannot help at all in your issue. Just out of curiosity, who told you you must be a supervisor to mount?
I’m familiar with the process for swapping between LTS, Zen, kernel from default. At the time I posted this I was using LTS. I have used Zen in the past. This was just an example for someone else who faced this issue and was relatively new.
The problem for me was understanding how to fix this from the USB, mounting, permissions, etc. I now have documented this and now know exactly what to do, should it happen again.
Again thanks to all who offered their help and suggestions. Much appreciated.