Startup/Side-Project Jams

"Game Jams" are a really popular thing, and many game developers enjoy participating in them. Most of these Jams are hosted online, and some of them even have cool prizes. Some great video games and communities are born from these events. It's a perfect place to test ideas, learn and build a following. I would love to see and participate in something like this for startups and side-projects.

Technically speaking I could easily create an online platform to host those Jams but I think for this idea to work properly these events must be hosted on an online platform that is already popular among founders, devs, and others - like for example Hacker News, Indie Hackers, Product Hunt among others.

Some founders are already doing their own challenges and marathons, so why not create a platform for it? I can be wrong but I don't think there is anything like this out there right now. What do you guys think?