I've made an open source AI chatbot for iOS and Mac. It comes with a 14 day free trial and then it's just $5 a month.
It has several features that are based on function calling.
1) It can read images using vision in order to answer questions.
2) It can generate calendar events, reminders, and contacts from natural language and images.
3) It can convert and edit media files using natural language.
4) It's completely private. None of your files or chat history are stored off your device and your conversations cannot be used for training.
5) The source is available on GitHub here: https://github.com/syousif94/iAsk
I would love to get some feedback and suggestions!