What URLs are allowed when a device is in isolation?

I am not sure if there is a definitive list for what you are looking for, but I will say that msense and defender cloud *wd* urls will be required access at a minimum. The full list can be found at the link below which requires unrestricted access in general- https://learn.microsoft.com/en-us/defender-endpoint/configure-network-connections-microsoft-defender-antivirus