LearnClash (https://learnclash.com) offers quizzes to be solved individually or in duel, or generated from a given topic.

A chatbot allows you to query the answers to explain or deepen them.

In duel mode, quizzes can be sent by code or played against random opponents.
Challenges to solve and points are awarded.

For iOS and Android. Based on Gemini.

In the free version, training and instructions to the chatbot limited per day.