You could upload this to the pico8 website, or export it as HTML5 and upload it to this site! (That's what me and a few other people I've seen have done).
Just type "export filename.html" in pico8 and it'll create an html and javascript file. Change the name of the html file to "index.html". Then edit the html file to remove the three line breaks (<br><br><br>) so that it will fit on itch.io properly. Then zip those two files together and upload!