I need to add fontawesome as a library because I only need to use a subset of the icons. What is the recommended placement of this /profiles/myprofile/libraries/fontawesome or /profiles/myprofile/modules/newmodule/library/fontawesome or /modules/newmodule/library/fontawesome?
Not sure if you are aware of this article that describes some library changes in Backdrop... That may help.
Yes, I had read this. Technically I would use the current font-awesome module but it's not included as a library but from a CDN. I thought because I need it installed as a library it should be in my installation profile as a module there, but I don't know if /profiles/myprofile/libraries is viable or not and I don't know whether I should work on another module for font-awesome as a library all can use that could be placed at /modules/font_awesome_lib or some other module name. Will /profiles/myprofile/libraries work or rather in a module in my profile?
The recommended way of using a library that's likely to be used by others (and I think FontAwesome qualifies) is to wrap it in a module. So creating your own font_awesome_lib module, installed at /modules/custom/font_awesome_lib sounds like a reasonable solution.
Or, if you're going to release the module as a contrib module, /modules/contrib/font_awsome_lib.
It might be nice if the font_awesome module offered a local-library (non-CDN) version as part of the module, as several other projects do, e.g., Bootstrap Lite. But I see the module needs a maintainer.