It has been announced that Superhot Mind Contol Delete is coming to Stadia in August 18. This was announced in a tweet. This is welcome news that the game is coming next week. Superhot is a current Stadia Pro game so you can pick up this expansion if you have enjoyed the original.
There is no pricing for the game on Stadia and no further details are available. You will need to buy Mind Control Delete if you picked the game up as a Pro title.