Here's a suggestion with 2 possible applications.
Had the idea when I played Kine but I can imagine this being useful in most solo games and adventures as well as Doom Eternal.
A) the developer solution
1) A player cannot resolve a puzzle in-game
2) After a while (determined by the game developer), the game detects that the player can't go through, and unlocks a "What to do ?" button. Player pushes the button.
3) The button opens a video inside the game which was uploaded by he developer on youtube. This video cannot be found through youtube directly, it is secretly uploaded. The video shows to the player what he has to do to go through. The video is streamed picture-in-picture in the game so the player does not need to leave the game. The video can be watched on every device (chromecast, mobile, browser).
4) Player advances.
Bonus idea : feature not available in hard modes.
B) the community solution
1) A player cannot resolve a puzzle in-game
2) The player can push the Assistant button to ask a solution.
3) Assistant looks into youtube using Google algorythms a walkthrough for the game and AI finds the right moment to show where the player is lost
4) Picture-in-picture video is shown and can be closed when pushing the Assistant button again.
5) Player advances
That would be awesome!!
Solution A requires dedication from developers (as in: time, and time is money), but it would be great to have at least solution B!
Anyway, I'm pretty sure that one or both of these solutions will come to Stadia eventually, as they have been officially presented by Google during Stadia's presentation.