Hello Daishiman, a non-profit called H4H (Hearts for the Homeless) is looking for help with finishing their app. [1] They work in disaster relief, mental health screenings, and vaccinations for the unhoused populations both in America and abroad. They actually already have some code written on GitHub. (To see, please contact kyle [at] h4hinternational [dot] org)
Disclaimer: I am Soobin, a co-founder of Nsustain, which stands for e[N]vironment and [sustain]ability. We connect people who work in high impact areas but need help with technology with people who have the tech knowledge and want to help.