Kernel_task running 100%+ which is throttling the MacBook Air

I'm sure this is too late to answer your question, but...

The error message is confusing, what it's really saying is "I can't find the type of the volume you want because I can't find the volume at all". As mentioned above, the volume name in the example doesn't match the volume name you have, which is tricky to find because the example doesn't post the result of the diskutil list.

Your info:

 5:                APFS Volume ⁨HD⁩                      15.3 GB    disk1s5

The info that would have shown up in the example:

 5:                APFS Volume ⁨Macintosh HD⁩            15.3 GB    disk1s5

Basically the example volume is called "Macintosh HD" and yours is called "HD". I'm speculating on the rest of this, since I can't reproduce that setup, but:

when you do the diskutil mount in the first command, you will probably get a directory named "/Volumes/HD\ 1". The slash after HD is just because spaces don't work in command lines, and the "1" is because there was already a "/Volumes/HD" directory, so when you did the diskutil mount you got a "/Volumes/HD\ 1". That means your next command would probably be:

sudo mount -uw /Volumes/HD\ 1

and in all following commands you would want to use

"/Volumes/HD\ 1" 

instead of

"/Volumes/Macintosh\ HD\ 1"

If this doesn't work exactly for you you can dig in and see what's in /Volumes, but hopefully this helps a bit.