Oppia: Teach, Learn, Explore
Open source tool for creating interactive lessons. The tool is designed to work similar to a chatbot, although you can have several different types of activities.
Character AI
I haven't taken time to play with this yet, but AI chatbots like this feel like a very promising avenue for personalized learning. Many of the simulated conversations that we currently build as branching scenarios could be practiced with chatbots like this. Language learning is another relevant area. This is currently in beta, but looks worth exploring.