Udhbhavaha is a an alternate learning space in Bangalore ( https://www.udhbhavaha.org)
The children who study here speak Kannada among themselves. I know two children who speak Hindi at home and now speak fluent Kannada. They learnt this in some 2-3 months after starting to go to Udhbhavaha. The video on the Asli Shiksha YouTube channel has more details. Check it out at https://m.youtube.com/@aslishiksha8820.