iChatWithGPT is a personal AI assistant that works on iPhone, Watch, MacBook and even CarPlay through Siri. It's got features like web search, text reminders, AI-generated images and voice control, so it can be a fixture in your life. It comes in free and Pro versions, so you can pick the version that suits your needs.
Another good option is Halist AI, which offers a fast and private ChatGPT interface for web, mobile, desktop and Chrome. It works on multiple devices and has tiered pricing, including a free tier that lets you use it 30 times a month. That means Halist AI is a good option for people who want a utility that works on a lot of devices and doesn't cost too much.