Possibility to add a custom channel eg. "LinkedIn PAID" that basically doesn't have any connecting function to actually post, but just enables us to create a post so that it registers in the calendar.

Globally, we have many standard posts to LinkedIn, in addition, we run a lot of global PAID campaigns on LinkedIn as well. Adding these non-connected "LinkedIn PAID" posts to the calendar would allow us to avoid bottlenecks when posting on the same day.