My apologies if this should be in the big picture or remote play forums or... anywhere else.

Goal:
Play a copy of Stardew Valley from GOG, using Remote Play.

Problem:
Big Picture detects Stardew Valley, but it detects the .exe file which doesn't properly launch. It should detect the start.sh file that exists in a parent directory.
I can customize this through the UI in normal steam and it works, but I can not customize in big picture.

Question:
Is there a way to customize the shortcuts in Big Picture to a completely different path/file (either through a file or the UI)?