Recommender system that connect users with each other , should I go for content based or collaborative filtering? I am trying to build a system where user come on the platform and he chooses a topic(predefined few topics) and then we connect him with any random online user who chooses the same topic. Then they can do conversation.

Now, I am trying to connect them smartly based on user's historical data (users with whom he had match earlier along with time duration of their conversation, and raing after the conversation etc). and his basic profile data.

How can I use collaborative filtering here, because I don't have any product here and their are very few users available online(10-15) at any time so I have to connect any one of them.

Thanks in advance!
You can use collaborative filtering with implicit features. However, I would first start with an even simpler approach. Maybe you could start using a distance metric, such as cosine similarity, or search for nearest neighbours using KNN.