Ygzeb replied to will future updates allow other players be able to fill out the Fog-of-war off your map and can you/they see the markers that you place? August 12, 2022 @ 1:21:32 pm PDT
Maybe you want to check the cartography table; it allows you to do everything you mentioned:
https://valheim.fandom.com/wiki/Cartography_table
https://valheim.fandom.com/wiki/Cartography_table
11:13 pm, August 12, 2022