Evening. Been going to Bavaria over the last 20 odd years, plenty to do and very outdoor friendly!
Obersdorf , Sonthofen are great and plenty to go at. Easy marked cycle tracks and running / hiking trails. Cable cars for getting up high and following the routes for walks or to mountain huts.
I normally go to Garmisch though, we did this Sept with our 9-month old. Plenty of walking with the baby carrier. We stayed in a village in Grainau, just about 5km out of Garmisch. Plenty to do in the area, easy travel from Munich ( we flew and hired a car, 90 minute drive ). You can get the train easy enough from Munich airport and once you’re in Garmisch it’s all easy to get about. Plenty of restaurants , supermarkets etc.
Theres a campsite south of Garmisch towards Grainau on the main road ( think it’s called camping Zugspitze ). Aldi across the road, right on the river, easy to get about. Stayed on the campsite in the past, showers, all decent facilities.
lovely place – enjoy.