> I don't know if this is possible on Steam Deck, but if you manage to open developer console (F12), there will probably be an error message explaining the black screen.
> Perhaps if you connect an external keyboard to the Deck?
> You need to export the game with DevTools enabled.
That's a good idea... Not sure if on SteamOS would work, maybe from Desktop mode... But definitely is something to try! :-)
UPADTE: SOLVED
How did you solve it?
Update:
I was using NW.js 0.82.0 and everything was fine until yesterday Steam Deck decided to give black screen.
I updated the linux version to NW.js 0.86.0 now it works fine. Greenworks (0.86) plugin wasn't working correctly (I probably used the old version accidentally since it was bundled with the project) so I replaced the "greenworks-linux64.node" with the file here: greenworks-prebuilds.armaldio.xyz
Now everything seems to be working. But 0.82.0 was like that too so I don't really trust it :D