Currently it's only possible to use delegate permissions to get chat lists, some requests need a signed in user to be able to fetch the information. https://docs.microsoft.com/en-us/graph/api/chat-l...
I agree with this one for sure.
We need a way to list all chats in the tenant especially GROUP chats, as currently the MSGraph API only allows listing the chats that a given person is a member of using application permissions.