Wasn’t sure where to put this exactly, but I’ve found that currently, no form of streaming gameplay via Steam Remote play is properly detecting any form of gamepad input. Playing locally on the streaming PC via controller works, as does using Steam Link via a Steam Deck and Android device for other games.
However in Grim Dawn, initially zero inputs are detected from the Steam Link app or simply selecting “Stream from another PC” on Steam Deck or another desktop.
Pressing Start on the controller however IS registered and will load the currently selected character from the start screen. You can then press start twice more, and then control the character, however bringing up any menu (the main pause menu or the item menu) kills control again. It can be restored by pressing the button once more to close whichever respective menu you’re in.
Essentially it looks like all forms of controller input that are in the “Menu” contexts of the game are failing except start/select when playing via Steam Link or Remote Play.
This behavior persists whether the option to use a Non-Steam Gamepad is enabled or not.