[maccard]

Unless I'm mistaken, Wikipedia doesn't ringfence their donations either, so by donating to the Wikimedia foundation [0] you're not just paying for wikipedia either.

[0] https://donate.wikimedia.org/w/index.php

[labawi]

If you donate to Mozilla, you don't pay for Firefox at all.

Conversely, AFAIK, Wikimedia doesn't accept money for merchandising their users. At least not in any official, straightforward way.