Sony Xperia 10 III with SFOS and Android support by Jolla (incl. Exchange and predicted text input)
Web browsing:
Default browser / sailfish browser or “Firefox Klar” (APK).
(Anglefish is using Chromium and I am not using Google based software if I can avoid it)
Chat:
Depends on what you mean by that. Fernschreiber (Telegram client), Skype (APK), WhatsApp (APK), Discord (APK)
Voicecalls:
Of cause SIM based telephone and Skype (APK) or Yottagram (Telegram client)
Maps and navigation:
PureMaps with OSM Scout Server and MLS Manager.