I honestly don't think this will be very easy to achieve on a human level. There are plenty of platforms that allow devs to meet sales partners but most people would rather just go at it alone or don't trust others or don't play well with others etc etc. Even the author of this piece, who testifies to poverty, chooses to ask for global donations rather than seek out a business partner

I think it would be something like "sign up with us and we handle the sales, support, billing, and invoicing".

Lots of open source projects don't need to bring on a business partner, but they might benefit from something like this. Just like not everyone on Kickstarter would go out and raise money by themselves.

The dev would presumably pay through revenue share, because we already established s/he is poor, making a jv where the marketing provider will ask for many adjustments from the dev because they need results fast. It's not a clear cut provider/client relationship and I'm not sure how many devs would choose to pursue this

A sales partner is different to a company that helps monetise.

And just because he is asking for donations doesn't mean he's against monetising.

Depends how you pay the company as I wrote above. If you're just a poor single man op you share revenue and that company becomes your partner

A webpage page with a list of projects that take funding, their licenses and how successful the funding is would be a great start.

Most people (think: GNU wizards) who do projects like this don't want to monetize; not for capability reasons, but for philosophical and social reasons. They think monetization is against some principal of free software, or their morals, or that people will stop using their software if they do, or, simply: they're lazy and just want to code, without worrying about menial things like income.

And then, when they can't afford to work on their project anymore, they want our pity. They don't have mine.

Is there a repeatable way to do that?