Volunteering as a vacation!

"Launched in 2007 as a series of weekend expeditions designed to assist Czech non-profit organizations, Tamjdem was founded by Štěpán Zelinger, an activist who was inspired by his own voluntary service in France."

https://www.expats.cz/prague/article/czech-tourism/how-to-make-your-summer-travel-more-meaningful/

This organization is Czech, but it was inspired by a French non-profit. The idea is international!