I believe I found the solution (they might have just added it).
You can find it within the object section of the custom object page (Accounts Dashboard | HubSpot).
Go to /crm/v3/objects/{objectType}
Here you just need to add the custom object’s internal name or the custom object’s ID.
As some people have mentioned, they can only see metadata. To see additional data you need to specify the additional fields (internal name). See the picture below.
