Our family of 5 will be in Garmisch for 1 week over Christmas 2023. Are there ways to volunteer for a few hours or a 1/2 day in a way that helps the local community? We're open to any type of volunteer opportunity.
I would contact the tourist information center with this sort of question.
Garmisch has been an American R&R spot since 1945, Everyone speaks English.
That being said, Christmas in Germany is a time for families and it's a small, local, community. It's not like NYC. Don't expect a lot of need for "volunteers".
Additionally, check the rules. In some cases, volunteering may be seen as "work" and that is not allowed on a general tourist visa.
This thread from a while ago brings up some good points:
https://community.ricksteves.com/travel-forum/germany/volunteering-in-germany-and-austria