Is there any SAP GUI virtualization solution alternative to Citrix?

Yes, customers can use AWS AppStream 2.0 (https://aws.amazon.com/appstream2/). for deploying SAP GUI and other front end components in a virtualized application environment. AWS Workspaces (https://aws.amazon.com/workspaces/) can also be used for a virtualized desktop environment and SAP GUI can also be installed here.

Further information can be found in the Deploying SAP GUI on Amazon AppStream 2.0 blog (https://aws.amazon.com/blogs/desktop-and-application-streaming/deploying-sap-gui-on-amazon-appstream-2-0/).

NOTE: This answer is provided by the SAP on AWS speciality team and is accurate at the time of publish. Please check comments as the answer may have changed/services evolved.