Getting members:

gh api orgs/uspdev/members --paginate --jq '.[].login' > data/members.txt

Repos:

gh api orgs/uspdev/repos --paginate --jq '.[].name' > data/repos.txt

Get contributors from every repository:

while read repo; do
    gh api repos/uspdev/$repo/contributors --paginate --jq '.[].login'
done < data/repos.txt | sort -u > data/contributors.txt

Find contributors who are not members:

comm -23 data/contributors.txt data/members.txt > data/outcontributors.txt