My side project NumPad https://numpad.io got me my current job at Decipad https://www.decipad.com/ (the similar naming scheme is a coincidence!).

I came across Decipad while looking for a job, and messaged the founder, highlighting my work on NumPad. They were impressed enough that the hiring process ended up being just a few interviews, I've been there for almost a year now, and it's been pretty good!

If there's a moral to this story I think it's that you should aim for work that's highly relevant to your side project experience. In my case both NumPad and Decipad have a sort of programming language that can do calculations with units.

But ignore this advice if you can't find that work, or it doesn't seem good for whatever reason. You can still highlight your side project in an application, and they might be impressed anyway.