Exactly what do you need?
If you want people to see your comic directly in the browser. From what I understand, the only way is upload it in html format.
As far as I know, itch does not integrate any type of player, that is, if you upload a .PDF or a .CBR, itch.io will not play it.
If you want people to download the file and open it with their computer, with their preferred program, then I understand that itch has no restrictions.