Ask HN: Where can I work for free?

Definitely agree with the other comments: it sounds like you're looking to contribute to open source projects. https://opensource.guide/how-to-contribute/ provides 'testimonials' from professionals who have contributed to open source projects - If you feel comfortable doing so, I'd encourage you to reach out to them for project recommendations, and pick something that matches your skill set + interests. Good luck!

I know it's not free, but you could do something on Fiverr. If you offer a lot of value for a small price, i'm sure people would love to have you help out.

Have you considered contributing to an open source project?

Open source projects would definitely be the way to go... what are your skills?