A new NGO started in the USA during the pandemic called Develop for Good. It brings together volunteer designers, developers and project managers who are currently in school and want real-world work experience. Disclaimer: I haven't worked directly with them, but from talking with theirt executive director and reviewing their case studies, I'm impressed. I've recommended them to all of the NGOs I work closely with.

There's an application form on their site if you'd like to submit a proposal. Please do reply back on your experience if you end up applying or even working with them. Thanks!