Dragon Quest XI has an extensive demo (about 10-15 hours) that lets you transfer your save game to the full game. Problem is the save transfer didn’t work on Linux last time I checked about 2 years ago. Maybe Valve fixed this since. Otherwise if you have a Windows PC you could transfer the save game there, but keep in mind you won’t be able to download the demo anymore once you’ve purchased the game. Welcome to the joys of Steam OS!