We’re in the process of setting up docs for Hosted Grafana, in the meantime this maybe answers your question?
Source IPs for whitelisting
If your corporate network requires external services to be on a whitelist to allow access, you can use the following lists to update your ACLs.
JSON format: https://grafana.com/api/hosted-grafana/source-ips
Text format: https://grafana.com/api/hosted-grafana/source-ips.txt
DNS lookup: src-ips.hosted-grafana.grafana.net
Those lists are always updated with IP addresses of the nodes on our clusters that might be running Hosted Grafana instances.