In open source I guess there's two types of work: 1. features 2. maintenance

You can 'sell' new features. They cost money to create, but they solve real problems. Those problems also cost money and if that's more than the cost of creating the feature, companies are willing to put in money (generally).

Maintenance is harder. But there are now some maintainer funds! Like the one from RustNL: https://rustnl.org/maintainers/ These are broader ongoing work and backed by many orgs chipping in a little bit.

Idk if it's the best model, but at least it seems to kinda work