Not sure if it can or not but I meant doing it rather on your PC once and then transfering modified saves to Steam Deck
- First you need to create some empty folder of whatever name in Grim Dawn / mods
- this will be your empty mod
On moving stash and characters I wrote here Item transfer between campaign and modded game? - #2 by tqFan
- illusions cannot be transfered although GDStash can add all illussions to your save
my other post on moving stash to Custom but with some helpful screenshot: Shared stash won't transfer between custom saves and main game - #2 by tqFan