I'm happy to report that the game will be released on 11 August at 12 noon GMT (well, BST to be precise).
This has been a long, long road (not as long as GTA VI's, of course, but y'know) so it'll be great to see the game fully live on Steam.
STEAM MACHINE UPDATE:
I'm now the proud owner of the new Steam Machine. It's a great piece of kit. Yes, too expensive, but great nonetheless.
And yes, The Comeback King works on the Steam Machine! It works really well, in fact.
INSTRUCTIONS FOR STEAM DECK AND STEAM MACHINE USERS
To run the game you'll need to set the Compatibility Mode to Steam Linux Runtime 1.0 (Scout). In fact, any Linux Runtime will probably do but this is the only option I get and it works for me.
On your device, go to the game and then click the cog for Settings.
Choose Compatibility.
Tick "Force the use of a specific Steam Play compatibility tool".
Choose "Steam Linux Runtime 1.0 (scout)" from the dropdown.
Install the game.
Do not try to install and run the game until you've done this: you'll be made to download a Web2View file, which is a Windows file and won't work on your device. If you have installed the game before setting the Compatibility Mode, uninstall it before going through the steps above.