Just spotted this thing: https://forum.effectivealtruism.org/posts/4PK3ykPsWWueutKgv/software-engineering-help-needed-effective-animal-advocacy

If it's just three days - and it's not like you'd want to work for a project outside of those hours - I'd suggest booking calls with as many EA's as possible who want advice getting started with software engineering.

Animal Advocacy Careers' "skilled volunteering" board has a few things that might be relevant in the "other technical" section.

https://www.animaladvocacycareers.org/skilled-animal-volunteer-opportunities

In general, you can become aware of these projects by joining the relevant Facebook and Discord groups. Please DM me for links.

What cause area are you most interested in?
Would you spend only those 3 days, or would you be interested in using those days to familiarize yourself with a project and be open to contributing more in the future?

You might be interested in https://www.impactcolabs.com/ , https://docs.google.com/presentation/d/1lSNKEP8RKgcQFROfpJFyN6VOuLxeQvybk_gqrDq8Tk0/edit#slide=id.g151144507d3_0_86 (AI Alignment, looking for 3 hours per week), and https://ea-internships.pory.app/board