As a related matter, there is also the NHS app, which seems to work up to the identification stage, where it takes a video of the user, but then the app doesn’t accept the result, saying “video file format not supported”.
This app is used to access medical records, including proof of vaccination.
The NHS Covid app uses the MicroG implementation of the (Google/Apple) Exposure Notification system. Instead of using the official MicroG GmsCore which includes this framework/functionality (and whic works very well), /e/ decided to make their own version of GmsCore without it, so that the user must install an “update” from the Apps store (either directly, or from the MicroG Settings page) to enable the framework, and allow the apps that need it to function properly. This page gives some more details, but it may not be up to date, and it may not take account of the problems and bugs that have been reported about the installation / update process.