Hello,
I switched platform from Windows 10 to Nobara Linux.
I would have expected that the savegames would carry over without hassle.
Especially as it worked to sync files from Windows 10 and SteamDeck.
Unfortunately the sync did not work and i had to copy the save game files myself.

To help others i put here what i did:

Steam told me via steam remotestorage which files it had synced and where they should be stored:

• %AppData%\..\LocalLow\SAYGAMES LTD\My Little Universe\Saves\

Unfortunately there was only 1 file registered, FileHierarchy.json, which i found and i had several more files and folders there.

I copied all of them to my linux corresponding subfolder in home-directory

• .local/share/Steam/steamapps/compatdata/2328750/pfx/drive_c/users/steamuser/AppData/LocalLow/SAYGAMES LTD/My Little Universe/Saves/Remote

Then i started the game and the save games were perfectly fine.
After i closed the game and checked the steam remotestorage all those files turned up.
So seems Steam Cloud Sync had an issue last time i played the game - without telling me.

Hope this helpfs someone!