Will Demo progress carry over?
The Chinese Steam Demo listing says save files can be kept for the full game. That wording does not yet provide a transfer procedure, an automatic-detection rule or a platform-by-platform promise.
Do not assume that a Steam Demo save can be moved to Switch, iOS or Android. Cross-platform carryover has not been specified.
Before moving a save
Keep your existing Demo save if you want to retain your progress. There is no established file path or manual-copy sequence to recommend here, so avoid moving or replacing save files based on a guessed location.
The Demo and release page links to the official Steam listings; follow the release instructions there when a transfer method is provided.