Create a shortcut to the game ( you will need to find the game in your itchio folder)
Right click the shortcut and select properties
Where it says target you want to put your cursor at the end and add " -vr" that's space dash v r. Your path to the game exe may need to be in quotes, if it does then add " -vr" after the quotation marks.
Now when you run the shortcut it should start in the Oculus