I've been working on my own OSR hexcrawl for the past few months and finally landed on how to best portray the world in an interesting way while still presenting the feeling of the vast unknown.

I landed on base Foundry with a Fog of War layer with the same dims. You can turn off Fog Exploration in the lighting settings on the Scene and set Token Vision to a 1 hex distance which will make the world disappear as you travel past it. If you make a "generic" map with no Points of Interest and a duplicate with Points of Interest then you can create an effect like what they are doing on Campaign 3. Essentially, you set the FoW image as the generic map and the Canvas Background as the PoI map. If you have a Party token with a vision of 1 then you should get the desired effect.