EKS Node group with x86 and arm/graviton based

Yes, you can change the launch template used by an existing node group. You can do this by editing the node group configuration and selecting a different launch template. To update the launch template, you can use the AWS CLI or an AWS SDK. For example, using the AWS CLI: aws eks update-nodegroup-config --cluster-name my-cluster --nodegroup-name my-nodegroup --launch-template name=my-launch- template,version=1

Yes, you can create a mixed node group that contains both x86 and Graviton-based instances. To do this: Create a launch template for each instance type (x86 and Graviton). When creating the node group, specify the list of instance types you want to include, and the corresponding launch templates

It is generally advisable to create separate node groups for x86 and Graviton-based instances. This approach allows better control over workload placement and avoids potential compatibility issues.