Dead Cells, GOG Version, Xbox One Controller Support
Fortunately, Debian Stretch does. Here is a simple way to force Dead Cells to use Debian's version of libSDL.
First, make sure that libSDL is installed
sudo apt install libsdl2-2.0-0
Then delete the game's shipped version (this is assuming that it is installed in the default location)
rm ~/GOG\ Games/Dead\ Cells/game/libSDL2-2.0.so.0
Dead Cells should then recognize the Xbox One controller without issue.