Only if they'd also spin off the browser from all the political activism and NGO cash grabbing, and let people choose themselves to which of the two their money goes.

Nah, they'd just increase the already ridiculous salary to their CEO.

On the other hand, people would be more inclined to donate money if they could trust Mozilla to value the privacy of their users, which is one of the biggest reasons people choose FF in the first place.

0% of donations go towards financing the Firefox project. Donations to Mozilla are explicitly not used for Firefox, they say so in the donation page.