The fear, uncertainty and doubt (FUD) against telemetry is unfortunately more sad than the FUD against Flatpak. I was already thinking of writing an article about telemetry is not evil last year, but I'll have to expand on how opt-in telemetry and "just ask your users" don't work well in practice.
I liked your article. Even tough my position is in favor of opt-in.
As contribution there. Is a linux distro that has had opt in telemetry for years now, Debian. You can do it during the install process or join after install.
the tool is called popcon; And even tough it is opt in, in the last 12 months it had about 25K submissions.
Which is a large sample compared with other attempts to get telemetry.
Check the graphic at the end of the page
@TheEvilSkeleton
An example of data collected by popcon:
https://popcon.debian.org/by_vote
https://popcon.debian.org/source/by_vote