The USHMM has tons of resources. https://www.ushmm.org/

I would start there. There's good articles on the camps to give people an idea of the size of the camp system and how diverse it was. There is a lot more to it than just the death camps and the scale is staggering. There's articles on the methods used to document the victims and to figure out the number of people who were victims of the Holocaust. They have first person accounts through diaries and oral histories. They have a collection of films, images and digitized original documents. You can find videos on their Youtube channel as well. https://www.youtube.com/c/holocaustmuseum/videos

I think it's a good resource to start people out b/c they have lots of essays on different aspects of the Holocaust that are written for a general audience.

Beyond that Ken Burns has a new documentary coming out PBS next month called The U.S. and the Holocaust. B/c it's a PBS thing they'll have resources for teachers and it should be easy to stream for free pretty easily after the initial release. https://www.pbs.org/kenburns/us-and-the-holocaust/

PBS is going to host some video panels that could be useful.

If you google around there's probably a local Holocaust museum or remembrance center near you that would have some local resources and suggestions. My local PBS affiliate has several documentaries about local survivors made in conjunction our local museum or regional Jewish civic organizations. And those organizations have a bunch of past events that are recorded and available to the public.

There's also organizations like the International Holocaust Remembrance Association that have resources from international partners in lots of different languages, Yad Vashem has resources for educators and lots of digital resources.

It can be kind of overwhelming b/c there is so much out there. That's kind of why I like to suggest the USHMM first b/c it's well organized to get you started.