What, exactly, are you looking for someone to do? If you’re looking at itch, their jam system handles most of the stuff that’s not on that list, I think? You click “create a game jam” and it asks you for a name and a cover image, start/end times, whether the jam has voting and who can vote, whether there’s a single score or if you’re ranking the game on multiple axes and so on. The jam will be hidden until you publish it, so you can take your time and play around with things, but I feel like they’ve done a great job of making it simple to host a jam.