Ask HN: How can open-source maintainers get paid?

I understand that the traditional route for open-source maintainers to get paid is to offer some sort of support plan to those who need it. Or accept donations.

However, support plans are great if you have a substantial project and donations are few and far between (take the GPG project for example).

So I'm wondering, is there a non-traditional way to getting paid for open-source work? Are there projects tackling this problem? Or is the only viable solution to take your code and close-source it?