This implies corporate sponsorship is a requirement for, as opposed to result of, a projects usefulness. That has not been the case for most valuable open source software.

Who sponsors curl?

GNU? Depending on how you want to treat FSF and PSF, gcc, emacs, python (are FSF/PSF/Apache corporations? Does PSF’s donations from corporations make python corporate sponsored?)

Never heard of Monero?

Keepass only allows donations, with no benefits for corporate vs. personal sponsors

GIMP is one of the most widely known & its sponsors only lists a few companies as hardware donors

VLC anyone?

OBS and Audacity (until recently) are two off the top of my head. Plus a lot of Linux components are run solely by a couple people, and those are run my millions of programmers.