Vantage will give you a break-down for every AWS, Azure, Fastly and MongoDB Atlas resource cost by category (i.e. Compute, Data Transfer, Storage) as well as fine-grained sub-categories (i.e. on-demand vs reserved usage, data transfer out to Europe, etc.)
See costs by category and subcategory for each resource and service
For each resource and service see costs per resource per day (compute, storage, egress fees) and subcategories giving you the specific AWS, Azure, and GCP billing codes.