Like many other European countries, Denmark also tries to track Sars-CoV-2 infections with a mobile phone tracing app. However, against advice by health organisations and despite positive examples by other countries, the app is proprietary, so not being released under a Free Software (also called Open Source) license.
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It is a bit concerning to see this news item referring to the existence of “positive examples” examples of contact tracing apps, IMHO, even if that might be related to privacy concerns perhaps out of the scope of FSFE. But it is not out of scope to point out, regarding the examples listed by the end of the news article, that, while licensed as free software, those solutions depend on non-free APIs:
Regarding UK’s solution, the trial was shut down and considered a failure, more info: https://www.bbc.com/news/uk-northern-ireland-53253628