Most of the time it's either it exists or it doesn't.

That actually sounds easy. Specially when you are the vendor and can choose what to bring to the device.

The nice thing is that, while Windows has a poor record at keeping compatibility each generation and requiring new drivers and maintenance provided by third parties (which doesn't sound "easy" for them), Linux keeps very stable and has accumulated an astonishing library of hardware support spanning decades.

It's amazing how I can plug almost any printer in a Linux machine and have it work out of the box, no extra drivers required, no nothing.

The most likely reason why Lenovo is choosing Windows is because they already have an ecosystem of crappy Windows software they typically preinstall in their machines and they probably expect they will be able to bring their own "special sauce" to hook some customers in... rather than just shipping with a more generic SteamOS that they wouldn't have as much control over & wouldn't give them an edge over competitors.