Ask HN: Moonlighting

Does anyone in HN have any experience in moonlighting? As an example, perhaps around an OSS project or technical stack you have some expertise in to provide services or consulting. Maybe as a side gig side until you eventually bootstrap a company around it?

I can see a lot of opportunities, but I would not be in a position where I can leave my permanent employment yet (living wage needs) but I know I could perform my job just as well.

How did you make the crossover?