Oh…I was dumbing this down for me 
. I had a similar question in my head like a week ago about how much space an add-on was taking up but that penguin fell off the iceberg. Your post popped this back up which reminded me so I did some sleuthing.
You can actually setup the HAOS SSH without a USB key.
So, what I did was use PowerShell to generate a key:
I then opened “id_rsa.pub” in Notepad, copied everything, and pasted it into the SSH add-on “Authorized Keys” from the “Configuration” tab.
From there, just follow the instructions in the post I linked.