One way to do this is to make it a part of a beta program rather than baked into the main app. That makes it slightly more manageable for the developers too.
That's true, but I don't know how many would bother installing the beta, especially given that most distributions use stable. This would be the same as opt-in telemetry.
Windows Insider already had over 10 million users 4 years ago[0]. I'd say that approach works well enough. I myself used it on Windows Phone 8, because some upcoming updates came with cool features and being in the Insider program gave me earlier access.
I also used Firefox Nightly for a while because of the massive performance improvements at that time. As Audacity claims they're doing it for UX improvements, it would be easy to get frequent Audacity users interested in a beta build featuring tracking but also all the improvements being tested.
