This is the most common method.
Grim Dawn offers several ways to share progress, ranging from internal game mechanics to manual file manipulation. Shared Stash Official Grim Dawn Guide explains that Smuggler NPCs Grim Dawn Save File Sharing
To host a Multiplayer session, select Host Multiplayer prior to loading a character into the world. To join a Multiplayer session, grimdawn.fandom.com Guide – Gameplay – Service NPCs - Grim Dawn This is the most common method
: Compress the folder (ZIP) and share it. The recipient must place it in their local Documents\My Games\Grim Dawn\save\main folder. Grim Dawn Save File Sharing
GD Stash is widely used, but any character touched by it gets the Cheater flag.