[tvanantwerp]

If a 501(c)(3) non-profit receives a donation for a specific project, by law they cannot direct the funds toward anything else unless the donor releases the funds for another purpose. This is more of a thing with large donations than, say, a recurring $10/month. If a small-dollar donor tried to restrict their funding, the non-profit would probably ignore the restriction because the donor has no leverage to find out if their instructions were followed.

If anyone with a ton of money wants to focus Mozilla specifically on Gecko, Rust, whatever, then that person can probably get them to do it.