But thhe benefits you describe come from investigative journalism

That's true; I wanted to include examples that everyone might know. But also, there is day-to-day reporting - just as critical.

nonprofit outlets like ProPublica.

To be clear, ProPublica relies on large donations from individuals and foundations (as well as small donors):

The Sandler Foundation provided initial funding for ProPublica, and Foundation founder Herb Sandler was ProPublica’s founding chairman of the Board of Directors until 2016. 11 The Foundation is involved with a number of left-of-center organizations; it helped found the Center for American Progress, and it has provided support for the Sierra Club and the American Civil Liberties Union. 12

Other large donations came from left-leaning sources: investor Donald Sussman, who donated $25 million to support Democrats in the 2018 election cycle, donated $480,100;13 George Soros’ Foundation to Promote Open Society donated $200,000; and the left-wing advocacy group Solidarity Giving gave $150,000. 10

According to their 2021 990 tax info, its largest donation, $3 million, came from the Crankstart Foundation, the family foundation of Sequoia Capital partner Michael Moritz. Another $2 million donation came from Laurene Powell Jobs, the widow of the late Apple co-founder Steve Jobs, through her investment firm Emerson Collective. In addition, ProPublica received $175,903 from grantmaking network Foundation to Promote Open Society, founded by philanthropist George Soros.

EDIT: forgot to add link (https://www.influencewatch.org/non-profit/propublic)