Oh, you can probably start with https://github.com/nostr-protocol/nips repository since there are many NIPs to learn 😅. You can probably pick some idea and start implement it even with simple PoC code, at least they can be useful for ourself. Hopefully we can create something better later for many people 🙂  

 Maybe try these, i am not a developer so i don't know, but people use it
https://github.com/nostr-dev-kit/ndk

https://github.com/nbd-wtf/nostr-tools 

 Yes, it will be easier to use those libraries to start nostr project instead of writing all the things from scratch 👍