I think we agree the engineers want their employer to fund open source. It's up to us to establish a new normal: if your company relies on open source technologies, you are expected to give back 0.1% of your revenue to open source projects. That's it.
Obviously, the challenge is to go from today's situation, where 0 companies give 0.1% of their revenue to open source foundations, to 1. Maybe an open source startup will be the first. Then a second. Then maybe the Google engineers can pressure Google to join this program. And maybe, just maybe, in 10 years, it's become expected, and most tech companies do it.
(a) 0.1% is an example, chosen to be low enough that it doesn't impact the financial results of the company, but large enough that it dwarfs all current donations to open source.
(b) if you are worried about the complexity of donating to multiple open source projects, you can imagine that a company could donate its share in one chunk to some open source foundation, which then redistributes among individual open source projects.