Looking for interesting ideas to work on for side-projects as an aspiring backend developer - eviltoast

Hi.

I’m a dev with 3 YOE, mostly in ML and MLOps, and more and more I’m trying to pivot into traditional software engineering. As of now I’m trying to really learn the fundamentals of backend engineering (as opposed to the bootstrapping DIY learning attitude that I had during my ML roles towards backend engineering), and I’m learning Node.JS. I’m getting familiar with the the concepts and the syntax, and so far so good. But one thing that I really lack is the imagination of what a good side-project might be.

So I ask experienced devs here, can you recommend me some good project ideas to work on, to make myself a better dev?