You're throwing out technical solutions – one law-technical, one crypto-technical – for what's essentially a social problem.
You don't need the draconian measure of dividing the OSS community, turning the idea of Free-as-Speech software into what's essentially shareware with source code access.
Large corporations have (obviously) vast financial resources. And – more importantly – they are (usually) staffed by humans. Have you ever felt the wish to be generous to someone whose software you used extensively? That feeling doesn't go away when you step into an office that requires a name tag to pass security.
Even mid-level managers or programmers usually can spend 4-figures easily without much oversight. And even if: I have witnessed a few cases where such requests went up the chain and came back with an added zero, despite HN third-favourite cliché being "companies have a duty only to shareholders and anything that deviates from 'greed is good' is a criminal offence'".
Sometimes it helps to offer a some sort of service contract, sponsoring or a workshop. They're bought as tokens to cover all eventualities.
So what's missing? Probably something like the FSF is doing here, handling paperwork and making it tax-deductible. I think it should be tied into some sort of coherent marketing strategy, kinda like the Apache foundation but more accessible to smaller projects, and possibly even a brand identity (/website) that doesn't trigger nostalgia for teletext. Mozilla is doing the best job in OSS marketing I can think of, but doesn't have a model for such projects. Maybe a Github foundation could also find success with a Wikimedia-style campaign. Although I'll hate myself for suggesting it if it ever happens.
Plus, unfortunately, a tiny bit of effort by developers. If you're just coding away at home and loving it, I can understand that it seems unfair, useless, out-of-personal-scope etc. that you should be doing fundraising. But it's also a bit too easy to expect good things to happen just because there's good code. (I have no knowledge of the octave situation specifically, and they may have done an excellent job and I'm wrong – this is just my general impression of some of these lone-coder projects).
Let's also not forget that OSS as a whole is probably doing better today than ever before. For every case such as this, there are dozens of cases where people are hired by large companies and largely left to work on their projects, or OSS created and released from within corporations, or successful startups with an OSS strategy etc.
Yeah, and "blockchain" isn't actually a magic spell that solves random problems...