Unsure of Berne, but in many Gemeindes / Stadts in Canton Zurich, there are special programmes under Asyl Koordination / Sozialdienste departments that a person with elementary German and perhaps with English can contribute to.

Such programmes are run by private organisations with support of both departments and deal with asylum seekers, refugee integration ( teach them IT literacy, job hunting etc. ) as well as assisting the youth groups and perhaps one can also be an observer in classes ( e.g. First Aid courses offered by the Samariterverein ) and then volunteer subsequently as the level of German increases.