I have to say I mostly disagree with your points.
At that kind of profit margins only the dividends get financed.
And I do spent the money on donations (FOSS devs, Wiki, random research, animal stuff), tho I haven’t though of donating to unions. I didn’t even know that is a thing. It isn’t where I live.
I understand they need to be financed, but the whole point of unions is to get a better bargaining position & thus finance. That shouldn’t need money. You dont donate to the strog guy that already has the power, you donate to the poor. Ot perhaps like some sort of semi-political parties that help organise workers? But we have regulators that strongly encourage unions at certain company size or sector.
What you can donate to or finance is smol studios. That’s boycotting the big studios, regardless of content consumption.