This part is related to what Mike said.
The OS is a perspective of the Storymind. The OS goal is about the goal of the mind, then, rather than the characters themselves. So the goal of the mind might be for only one character to learn. That’s why you may see one character for it, one against, and a bunch of others connected to or wrapped up in it, like Mike said.
If they are an OS character, they don’t need to be actively involved in the pursuit of the goal. They just need to feel conflict that stems from that Concern. The conflict is is what wraps them up in it. Also consider that characters don’t have to seek learning. They can just learn without even meaning to. And that can be the goal.
This part is related to your question, but perhaps isn’t a direct answer.
@jhull has recently written an article explaining that the RS is not required to carry the MC or IC. The RS is it’s own separate thing. I believe the OS can also be described as its own separate thing. What I mean is, just as the RS requires neither the MC nor the IC players, neither does the OS require those players. It is an objective impersonal view of the problem separate from the MC, IC, or RS views and can even be referred to, as I’ve recently found, as the it perspective.
As a separate perspective, it doesn’t even have to cover the same type of storytelling as the other perspectives. This is covered elsewhere on this forum, but you could have four different throughlines that look like four completely different stories, but because they all fulfill their dramatic function within the Storymind they will still get the message of the story across. So what’s important isn’t that every player in the story be involved in the goal, but that every character that carries a dramatic function of the OS perspective be involved with the goal.
As an example, look at Saving Mr Banks. You might be able to argue that Ralph the limo driver is somehow concerned with getting P.L. Travers on board with Disney’s vision for a Mary Poppins movie and this falls under the OS, but I wouldn’t be surprised if his role is strictly within the RS, a growing friendship with P.L. Travers, meaning he wouldnt have to deal with Psychology (or whatever the OS turns out to be) at all.