Are there any incubators for nonprofit startups?

What's the nonprofit? I think people would be interested if you'd like to share.

You should definitely apply to YC. Email hn@ycombinator.com and we might be able to advise a bit. (Same offer for anyone. Just realize that the inbox is hell and it may take a long time to reply.)

Several.

FastForward is probably the largest and furthest along in organizing around Tech Nonprofits specifically, with a pretty solid base of alumni success stories(https://www.ffwd.org/).

I'd also look at Visible Connect, which is tech nonprofit focused. Full Circle Fund, if you're in the Bay Area. Since you mentioned you're in Education, you should also look at the Aspire Accelerator, which isn't exclusively tech nonprofit but includes many tech nonprofits.

You could also consider YC which has taken a few nonprofits.

YC supports both edtech and nonprofit companies. I am the partner at YC who handles those two areas. Let me know if you have any specific questions. I helped start Imagine K12, which was an edtech incubator (that also worked with edu non-profits) that folded into the YC family back in 2016. There are other edtech and non-profit incubators: LearnLaunch is an edtech incubator based in Boston, Fast Forward is a tech non-profit incubator in SF.

YC has had non-profits. I think Watsi was the first.

https://watsi.org/

Mozilla's got one.

https://builders.mozilla.community/

If it's about the supporting the open internet in particular, the NLnet Foundation comes to mind. https://nlnet.nl/

There's one called charity entrepreneurship