I don't work on personal projects on my own time, but I do work a part time hourly job alongside my software engineering job. I've found for me this is an essential part of my mental health. My arrangement offers up a little more variety than I'd otherwise have and allows me to work with another group of people in a totally different domain.
Also, I've found the best opportunities come through word-of-mouth connections, and having 2 sets of colleagues essentially doubles the chances of that happening.
For many years, I worked at the Park Slope Food Cooperative (https://www.foodcoop.com/) several hours a month, which was a great orthogonal use of my mind. I started as a box-breaker, got promoted to an olive processor and finally became squad leader for Olives & Cheeses. The whole experience was like using a completely different part of my brain.
They tried to get me to join their technology group, which i rejected :-)
Also, I've found the best opportunities come through word-of-mouth connections, and having 2 sets of colleagues essentially doubles the chances of that happening.