How to search for ideas for a pet project?

Question

Backend

I am a NodeJS backend developer and have no ideas for projects. Googled for a long time, all the answers that I received in the browser look to me like "make a todoList / make another useless social network", or like "write an engine for Elon Musk's rocket". I persuaded myself to write a simple project - a backend application where users can upload their books and download others (CRUD with a PostgreSQL database and GraphQL apishka), I started with a simple one. I finished writing this application (actually, I need to finalize it, but it doesn’t matter) and I don’t know how to develop further.

PS I am looking for ideas not necessarily for NodeJS applications. I would like to feel what Rust and Blockchain technology are like, but there is no understanding that (at least a little) useful I can develop on this. I just don’t want to make a useless program, just for the sake of a repository on github