Every job I’ve ever had has been because of hackathons. Either being directly approached by a sponsor at a hackathon, or being remembered by someone involved with the hackathon after the fact. I briefly did a stint in a wildlife conservation NGO and even that came about because I had helped out at a hackathon at a zoo once.

I don’t think hackathons are particularly unique, I’d abstract this to “be visible and known in your tech community”.