With the amount of fuck-ups from Microsoft, this might not be necessary, but:
The average user doesn't want to install the operating system or doesn't care about it as long as they can do their things, and those who care can easily do so today. Thus, IMO, advertising to the end user is a waste of resources.
Focus on permeating it in governments, institutions, and OEMs to increase market share and break the "Linux is complicated / incompatible / for developers" stigma, then organic adoption out of these environments will grow - at least among people who can actually use it with the supported software.
I'm a die hard Linux user. I don't spend much time telling people about it outside of actual tech conversations that should include the topic. I did raise my kids with a lot of Linux desktop use on their machines. They uniformly find the Windows 10/11 experience to be horrible, so I guess I've managed success on that front.
There's a circular reasoning happening that's causing Windows to stay dominant. Why isn't professional software being developed for Linux more? Because it doesn't get used in the workplace. Why doesn't Linux get used in the workplace? Because it doesn't have professional software support.
Hm it's probably "bundle with the hardware, make sure the hardware really works and there's a price incentive vs Windows".
As long as you have to actively migrate (including backing up, losing access to several commercial apps) and could end up in the situation that your hardware isn't 100% working or you're workflow isn't really supported?
Linux is the most used kernel on the planet - and it’s not close. Just the Android phones are enough to get a comfortable lead. Add the embedded systems. Add the servers. The competition is severely trounced.
The few desktops left and right are just slivers of the complete domination that Linux exerts over commercial operating systems.
Pretty much the entire internet runs on Linux already.
For personal users I think a stable, well supported, secure and privacy focused version will help. Also, it helps if this is the version your "computer-guy" uses, the guy that you (or your mom) call(s) when your computer is broken.
Another “Steam Deck is the reason” failure to cover the fact that once Steam Deck dies out it’s users also leave. Valve has awful hardware history and Steam Deck itself only runs games because they are the ones paying for Proton. It should not be controlled by a company that is known to make you lose your games.