They are "going hard" the way I see it. Without Valve doing legwork behind the scenes and collaborating with anticheat developers we wouldn't even have Apex Legends running on Linux like we've had for a year and a half. They've been talking about wanting to use Linux as a viable PC gaming platform to escape Microsofts lockdown of their platform since the days of Steam Machines when Windows 8 and the new store app were giving bad signs.

Either way Valve would be silly not to provide a compatible way to use Windows on the Deck. Even though the situation is much better these days, they know very well that a lot of enthusiast PC gamers would be dismissive of the Deck if Windows couldn't work properly on it and that word of mouth would bring less confidence in the product.