While we understand the SPS uses minimal recommended resources (4 CPU/8GB Memory), please know that for AWS deployment, Service Gateway supports the following instance types:
C3.xlarge
C3.2xlarge
C3.4xlarge

Help article about Service Gateway appliance system requirement for reference:
https://docs.trendmicro.com/en-us/documentation/article/trend-vision-one-deploying-a-sg-aws-a

Please have the customer enable the "All generations" option when choosing the instance type during the EC2 launch and see if they can search c3 types. If not, this is a limitation on the AWS side. Hence, we don't have any control. For example, Asia Pacific (Seoul) — ap-northeast-2 region, C3 is not available according to their documentation.
https://docs.aws.amazon.com/ec2/latest/instancetypes/ec2-instance-regions.html

We suggest that if customer can't use the default instance type, deploying SG on other regions can be an option. We can only recommend specific instance type since not all can be selected also on our end so tests are only done on the instance types being recommended.

Development Team are still making progress to be able to have workarounds for this AWS limitations.