Just getting my feet wet first creating user accounts maybe first and move on writing a simple client or a relay query tool. Start dmall and build it up.
Discussion
I'm not sure why ChatGPT suggested react. It can help with the front end, but it's not a requirement, and personally I'm not at all fond of it haha.
It's also far quicker to get familiar with coding nostr without spending hours building an interface. Code the core logic and just pump out the results or summaries to via console.log or command line. Then start designing a UX and UI based when you've got a better idea what you're building.
What languages are you most proficient in? If you want to use JavaScript, there's a great nodejs library https://github.com/jb55/nostr-js