Crowdfunding does that. The product costs 0 once the funding threshold is met and the money is secured, but before that it costs >0 if you actually want the product to be developed. This aligns incentives quite well, if the model is used correctly.
All of the crowdfunding projects I've participated in delivered a product (games, books, albums, hardware) that was sold as a normal product would be upon completion with the backers getting their rewards.
Patreon is maybe more what you're describing but that's not usually product-focused and is more patronage as the name implies.
Here is a Kickstarter crowdfunding campaign that resulted in open source code being added to the Linux kernel. This is from a company that usually does the same sort of work but is usually funded by other companies.
Free speech implies you can't force it to be not free as in beer. Being allowed to charge money for something doesn't prevent other people for giving it away free.
True, but there are a large number of people for whom just running "make" at the command line is too much of a hassle. This is normally the market, not other technical people.
This really doesn't work and it's a disservice to mention it. Every time someone has tried to withhold binaries other people step up within hours to provide them (whether that's a good thing or not).
I'm unaware of any economic model that allows a product or service to cost 0 but simultaneously net the producer > 0.