Dicio is a free and open source voice assistant running on Android. It supports many different skills and input/output methods, and it provides both speech and graphical feedback to a question. It uses Vosk for speech to text. It has multilanguage support, and is currently available in these languages: English, French, German, Greek, Italian, Russian, Slovenian and Spanish.
Available on F-Droid, Google Play, and as an .apk file from Github.