FOSS Funders is a community of companies that sponsor FOSS maintainers and projects: https://fossfunders.com
The EU framework research programs have strongly favoured FOSS contributions. It's certainly not the most straightforward application process though and competition for the grants outside niche domains is cutthroat.
FUTO is a newer player in this space: https://futo.org/
Where do the finances for foundations like come from? Purly donations? Or is it government funded?
This is a key information one would be looking for on the site, but i cannot find it.
FUTO is funded by billionaire Eron Wolf. There's an interview[1] with him on their YouTube.
The NLnet Foundation supports organizations and people that contribute to an open information society. It was influential in spreading the Internet throughout Europe in the 1980s. In 1997, the foundation sold off its commercial networking operations to UUNET (now part of Verizon), resulting in an endowment with which it makes grants.
https://en.wikipedia.org/wiki/NLnet