The map then shows only what you have explored, with your in-game pins. Your files are read here in your browser and never uploaded, whatever the folder dialog calls it.
C:\Program Files (x86)\Steam\userdata\<number>\892970\remote
userdata: open the one numbered folder there, then 892970, then remote. Steam on another drive? Start from that Steam folder instead.%USERPROFILE%\AppData\LocalLow\IronGate\Valheim <name>.fch from characters and _main.<number>.fwl2 from worlds\<World>. Consoles keep these files out of reach.