Neither is an income stream, and Rust was evicted while it was still taking off and is no longer a Mozilla project.
If there are users, and there is a need, we should directly furnish the project with a bunch of hired employees rather than indirectly pay some manager, rely on charity or ads.
Yes, I know, how unamerican of me. ;)
Who is “we”?
It might also be possible to fork and spin off Firefox into a new non-profit, circumventing Mozilla if some of the devs organize it.
Money is fungible. If you want to do this, frankly, donate to LibreWolf.
Neither is an income stream, and Rust was evicted while it was still taking off and is no longer a Mozilla project.