FWIW on AWS, all nitro instance types can boot as UEFI if the AMI has itself set to use UEFI and all arm64 instances only support UEFI. So if you stick to modern instance types, you can happily use UEFI in AWS.
GCP looks like it does UEFI too. And Azure Gen2 instances use UEFI too.
GCP looks like it does UEFI too. And Azure Gen2 instances use UEFI too.