What you are looking for is some sort of variant of quadratic funding. It is a mechanism that is specifically designed to overcome the free rider problem that public goods like FOSS suffer from. It solves it by matching private contributions to these public goods using a special formula that aligns incentives, so that everyone that knowingly benefits from a public good has an economic incentive to contribute to it because more contributors leads to a higher level of matching

I disagree that the 2 options are the only ones available. We could have a funding system with aspects of quadratic funding and artistic freedom vouchers, which allows the organizations developing the software to remain private organizations. Quadratic funding is basically a public matching fund for contributions to public goods such as OSS with a special matching formula that matches small contributions from many sponsors at a higher rater than more concentrated ones

What I meant was blacklisting certain destinations. It obviously wouldn’t prevent all malicious traffic

Would it be possible to allow exit nodes to blacklist specific kinds of traffic and somehow privately verify that the traffic is not one of the blacklisted kinds (zero knowledge proof perhaps sorry not a CS person)?