The hardware vendors should just offer OS choice at checkout time, and revenue sharing for the resulting choices.

I don't disagree, but without some sort of formal or official support from the distribution, I think this is a tall ask. Some vendors have shipped Ubuntu and Fedora on laptops, but not many. If they were going to truly do this, I think it's reasonable for them to expect a minimum level of support from the parent company behind the operating system. Even just for training and bug purposes, people could easily end up getting an OS they aren't comfortable with and complaining at the laptop vendor for it.

That is definitely the wrong approach with the Linux ecosystem, and any other open source ecosystem. Not all distros actually have a single parent company, or any parent company, many are volunteer only but accept donations.

The right approach would be for the laptop vendor to test their laptops with distros requested by their customers, and to contribute new drivers and fixes to the mainline Linux kernel and other upstream projects, and to require their chip suppliers to do the same. The revenue sharing could be via an official partnership, or conference/etc sponsorship arrangements or even just regular donations.

The OS selection would probably have to be hidden behind an "advanced community supported options" area, to reduce the confusion you mention.