Hmm, there's supposed to be a Tasks [reminders] feature in ChatGPT, but it's in beta (I don't have access to it). Whenever it gets released, you could make some kind of "router" that connects to different communication methods and connect that up to ChatGPT statefully, and you could just "speak"/type to ChatGPT from anywhere, and it would send you reminders. No need for all the extra logic, cron jobs, or SQLite table (ChatGPT has memory across chats).