After going through a lot of trouble, I find myself in another hurdle where I absolutely need cloth simulation to be displayed into sketchfab.
I have done a lot of failed trial and error uploads, and hopefully this works**. I am hoping exporting my cloth as a .abc file then importing that same file back to blender does the trick for a cloth-physics work-a-round**, and that it will animate itself in the sketchfab viewport. (Currently uploading, will update progress)
As oppose to the work-a-round being mentioned in this post : https://blenderartists.org/t/how-to-convert-a-cloth-simulation-animation-to-keyframes/600133/2 using 1 shape key for each frame.
(white cloth = .imported .abc format)