You can volunteer to work online directly with UN related agencies around the world through UN Online Volunteering.
The United Nations Volunteers (UNV) programme contributes to peace and development through volunteerism worldwide. Online volunteering allows organizations and volunteers to team up to address sustainable development challenges – anywhere in the world, from any device. Online volunteering is fast, easy – and most of all, effective. When skilled, passionate individuals join forces online with great organizations working toward sustainable development goals, everyone wins.
Find out more at https://www.onlinevolunteering.org
For a list of current opportunities see https://www.onlinevolunteering.org/en/opportunities