> [In Igalia] we have the ability to submit for investments for things that nobody is currently funding but we think deserve funding and deserve to move forward somehow. [...] Initially this came up about doing some work on MathML in WebKit [sic; Blink presumably]. That was years ago. We sponsored all that work, funded all that work, got it done. And then, there was another effort there to try to drive something forward enough to make a proposal and maybe fund it through grants and crowdfunding. So we did an initial thing based on also writing a grant and getting initial money for the project from the National Institute of Standards Organizations and the Alfred P Sloan Foundation. [...] Then we also got small amounts of funding, few thousands from Pearson and APS Physics. And then there was a period where there was no more funding to be had for about a year, year and a half. And so Igalia stepped back in and funded the work. It slowed down slightly toward the end there, but we kept it going the whole time. And then we started Open Collective.
(https://www.igalia.com/chats/mathml-release)
It seems like some of the work that Igalia did was externally funded, but far from all of it.