I have a .styles file that I have been using in ArcGIS Desktop that now needs to go up as a default category to my organizations Portal for ArcGIS. I wasn't sure if there was a standard way described to do this, but I would like for my custom symbols to show up as part of this list below -

I did find the below article useful, kind of, but it loses track when I am trying to publish the symbols as a new item to my portal and I realize that the type 'symbol-set' isn't available at all.
How To: Configure Portal for ArcGIS with custom symbology
All I could manage to do was publish the .png corresponding to one of my symbols as an Image File.

I do find a lot of results of the type 'Style' on AGOL but cant really figure out how would i publish something similar and then eventually add it into my default list of symbols.

Any suggestions or help will really be appreciated, thanks !!!