I work as a software developer. Since our software is not as well known as Freeletics, our roadmap is not published either, but we generally announce our next steps in the event of inquiries.
For software that is as well known as Freeletics, I have often seen public roadmaps with feature requests (e.g. Highcharts Roadmap | Highcharts). It’s not about details, but about alignment, what your focus is. Depending on this, feature requests are then submitted.
As a first step in this direction, it would be awesome, for example, if you could create a “feature and bugs” category and enable technical discussions there. I “often” notice problems and bugs, but the official bug path is too strenuous for me for little-stuff and I also miss transparency about what exactly is fixed or updated. Maybe a public changehistory would be amazing (e.g. https://www.highcharts.com/blog/changelog/)