Can I sign up for this event through Eventbrite if I'm a developer that wants to pitch?

Unfortunately, this isn't possible, the application and selection process for the pitching studios is done by the respective co-organizer of the session and subject to strict criteria.

Can I watch the session if I'm not a publisher, investor, platformholder, or a similar company?

Unfortunately, this isn't possible unless you are an invited guest by the respective co-organizer, the session is done in private and access is strictly for companies that can provide funding and/or publishing services.