Re: Mass Effect Legendary Edition offline workaround

Launching EA App on PC at least, putting it into offline mode, SHOULD allow you to launch your games without issue.  I just tried doing this on OE ME and LEME games, and had zero issue.  I don't know if it being steam deck makes any difference, or how it integrates between steam and EA app. 

Have you tried launching directly from EA app with the EA app in offline mode?