The effect of that would be next to none. It's all about OEM preinstalls. >95% of people never install an OS on their devices themselves. They use whatever is on it. iPhones come with iOS, Samsung phones come with their specific version of Android, and in >99.9% of cases it stays that way. You wouldn't even see the tiny amount of people installing, say, GrapheneOS on their Google Pixel.

It's similar with laptops or desktops: Windows is preinstalled on most of them, so that's what people use. The only other relevant OS in terms of OEM preinstalls is macOS. Heck, most people don't even know the manufacturer of their laptop unless it's a MacBook. It's either a MacBook or an "Apple" or it's simply a "laptop".

There are some OEMs (Lenovo and Dell come to mind) offering Ubuntu or maybe Fedora preinstalled on some of their models, but I never saw it listed as the default option.

The best way to get people to use Linux is to preinstall it on a device people want to use. A very recent example of this is the Steam Deck. Most users don't care or probably don't even know it runs Linux, it just does what they want it to do. Most people likely don't know their Chromebook runs Linux, or their Android phone (that they call a "Samsung phone", not an "Android phone").