Cross save allows you to pick one account to be the cross save account. The characters, inventory and game progress on that account is all you will see when you log in on the other linked platforms. So if you picked XBox then all you'd see when logging in on Steam are your XBox characters, inventory and game progress. Your Steam characters, inventory and game progress would then become dormant and unusable. When you disable cross save then your XBox characters would go back to XBox and your Steam characters would become active again. However, nothing transfers between accounts when cross save is on, so your Steam characters, inventory and game progress would be exactly as it was right before you enabled cross save. Bungie does not offer any service to transfer characters, in-game items, or game progress between platform accounts.

Hi there. Enabling Cross Save with your Xbox characters set as the Active Account would make your current Steam characters and their progress/gear inaccessible. Cross Save does not merge anything between your accounts, and transferring items or characters between accounts is not possible. Please refer to the information on the following pages for more information. https://www.bungie.net/7/en/CrossSave https://help.bungie.net/hc/en-us/articles/360048717732-Deleted-Item-and-Character-Policy