A great many amount of people use Android to this day because of its more open nature, and that's despite Google's involvement. If Motorola could go back to its native roots, shake the idea of Chinese influence, and do open source proper, I bet there's a lot more than 5% of the market ready for it.
(I would bet more than 5% have at least a vague notion of open source though, and a positive a priori - also possibly mixing it with source-available, which would be on par with some people we can read on HN)
Take away open source and there would barely be a large tech company left standing.
The downstream effects of something being open source might acquire users, but being open source in of itself doesn't do anything except for a very tiny slice of the population. I'd say (in the US) more than half of the software developers I know use an Apple phone despite Android being much more open.
Whenever I'm on HN I feel like most of the posters here live in a bubble where they think most people are anywhere near as tech literate as they are. (You can really feel how this forum is SF-coded).
> The downstream effects of something being open source might acquire users
So labeling means nothing, but open-source is important to users. See also: enshittification.