Well there are contact tracing apps in the Play Store, so there isn't a blanket ban. Google and Apple famously have added an API for building such apps in a way that doesn't involve a central store of user's personal data, and some countries developed apps of their own which were less respectful of privacy but still made it into the Play Store (albeit in the UK's case only on a trial basis before being withdrawn, but that wasn't because Google forced them to). So as a general principle Google do allow such apps. But I don't know whether there are other specific restrictions that might limit who can do this. This is why I asked whether you'd tried asking Google (albeit with the warning Google aren't famous for being the most responsive and communicative company).
