Depending on who you ask, its at ~2% today. If that feels high to you, remember: it includes Chromebooks.
As it grows, you'll absolutely hear people say "Chromebooks" or "Steam Decks should be their own category, they don't count". These arguments effectively reduce to "Linux cannot be popular, so I'll move the goalposts so it never is." Ignore them, and pour cement around the goalposts: running a distribution of gnu/linux.
Of course, if all we cared about was the "linux" part of gnu/linux, then its already the most popular operating system kernel in use by mankind. Its already won.