How can I add a Savegame Location for the Steam Deck? (SteamOS)

[bisonfan95 0]

Whenever I try to edit to something like this:

===Save game data location===
{{Game data|
{{Game data/saves|Windows|{{p|steam}}\userdata\{{p|uid}}\816020\remote\}}
{{Game data/saves|SteamOS|{{p|steam}}\userdata\{{p|uid}}\816020\remote\}}
}}

It tells me that the OS is invalid. Not only that, the savegame section forcefully inserts a Steam Play section (that is technically the Steam Deck section since it also uses Steam Play) and inserts automatically wrong information. Not every single game that uses Steam play uses the savegame location listed: 

Steam Play (Linux)	<Steam-folder>/steamapps/compatdata/<gameid/pfx/[Note 1]