Yes! The DLCs are rpa files which can be found in your Steam directory. You should be able to find them if you right click on Our Life in Steam, click on Properties > Installed Files > Browse > and then the directory should open up. In there, click on the "Game" folder, and look for the files with the .rpa ending. Move those into the "Game" folder of your itch.io version, and that should work. If you need more help, just let me know!