If you just want to see what your seed looks like there is another way. https://valheim-map.world/
As far as have read about it and can recall, the world is created for 500m around you as you explore, so coming within that distance of a feature makes it populate. So yes you can reveal the map, but until you approach 500m of something it is not there.

BTW: not 100% sure it was 500m.