You can send your spy to spy on other kingdoms. I do think the game should have a radius of 1 county 100% visibility and degrades by counties further away of your knowledge AND a court positions would increase the knowledge and accuracy of information. Court Positions such as Trade Manager (Network of trade with other non-realm rulers), Information Broker (Network of information gathering), Option to establish a spy ring in another county for cost.

Dunno...just spit ballin here

Look for mods with 'fog of war'. There are mods that even start with you knowing nothing beyond the character portrait - not their skills/stats/traits, nothing about the kingdom/duchy/county, etc.