The Amazon Linux 2 AMI with .NET Core has been updated to include Mono, an open source implementation of Microsoft’s .NET Framework. The AMI comes pre-configured with .NET Core 2.2 (with Long Term Support), Mono 5.18, PowerShell Core 6.2, and the AWS Command Line Interface (CLI).  

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/09/amazon-linux-2-ami-with-net-core-includes-mono/