It would be great to have an automation when subitems can be converted into items based on some conditions. For example, when item created and only if it contains subitem, then move only the subitem to another board converted as the regular item.
We developed an app called subitem automations that provides robust automation capabilities to subitems. It also includes the ability to convert subitems to items and vice versa here’s an example.
Convert subitem to item →
Convert item to subitem →
You can find it in the monday.com marketplace in the platform or here - monday.com: Apps Marketplace
Hope that helps!