I'm quite surprised how many up-to-date applications can be installed via APK files or alternative markets (F-Droid) and work. For instance, thinking of Threema

I'm quite surprised how many up-to-date applications can be installed via APK files or alternative markets (F-Droid) and work. For instance, thinking of Threema or Whatsapp, two continously maintained applications which do not inevitably depend on GApps.